Tag Archives: education

Less inspiring people in universities than in early school

A student claimed that fewer inspiring people are found in universities than in early school. Empirical checks of this would be interesting and would need a measure of inspiringness. A theoretical explanation is a tradeoff between multiple dimensions: subject matter competence, integrity, reliability, communication skills, being inspiring, etc. The tradeoff is on both the demand and the supply side. An inspiring competent person has many career options (CEO, politician, entrepreneur) besides academia, so fewer such people end up supplying their labour to the education sector.

On the demand side, a university has to prioritise dimensions on which to rank candidates and hire, given its salary budget and capacity constraints on how many job positions it has. Weighting competence more leaves less emphasis on inspiringness. Competing universities may prioritise different dimensions (be horizontally differentiated), in which case on average each institution gets candidates who have more of its preferred dimension and less of other dimensions.

As a side note, what an organisation says its priorities are may differ from its actual priorities, which are evidenced by behaviour, e.g., who it hires. It may say it values teaching with passion, but hire based on research success instead.

A constraint is a special case of a tradeoff. Suppose that given the minimum required competence, an employer wants to hire the most inspiring person. The higher this level of competence (teaching PhD courses vs kindergarten), the fewer people satisfy the constraint. At a high enough level of the constraint, there may be insufficient candidates in the world to fill all the vacant jobs. Some employers cannot fill the position, others will have just one candidate. Maximising inspiringness over an empty set, or a set of one, is unlikely to yield very inspiring people.

It may be inherently simpler to inspire with easier material, in which case even with equally inspiring people throughout all levels of education, the later stages will seem less inspiring.

Larger leaps through theory may be required as a subject gets more advanced, leaving less scope for inspiring anecdotes and real-life examples. The ivory tower is often accused of being out of touch with common experience. Parting with everyday life is partly inevitable for developing any specialised skill, otherwise the skill would be an everyday one, not specialised.

If inspiring people requires manipulating them, and more educated individuals resist manipulation better, then inspiring people gets more difficult with each level of education. Each stage of study selects on average the more intelligent graduates of the previous stage, so if smarter people are harder to manipulate, then those with higher levels of education are harder to inspire. On the other hand, if academics are naive and out of touch with the ways of the world, then they may be easier to manipulate and inspire than schoolchildren.

People accumulate interests and responsibilities in their first half of life. The more hobbies and duties, the less scope for adopting a goal proposed by some charismatic person, i.e., getting inspired by them. Later in life, many goals may have been achieved and people may have settled down for a comfortable existence. They are then less inclined to believe the need to follow a course that an inspiring person claims is a way of reaching their goals.

Contraception increases high school graduation – questionable numbers

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In Stevenson et al 2021 “The impact of contraceptive access on high school graduation” in Science Advances, some numbers do not add up. In the Supplementary Material, Table S1 lists the pre-intervention Other, non-Hispanic cohort size in the 2010 US Census and 2009 through 2017 1-year American Community Survey data as 300, but Table S2 as 290 = 100+70+30+90 (Black + Asian + American Indian + Other/Multiple Races). The post-intervention cohort size is 200 in Table S1, but 230 in Table S2, so the difference is in the other direction (S2 larger) and cannot be due to the same adjustment of one Table for both cohorts, e.g. omitting some racial group or double-counting multiracial people. The main conclusions still hold with the adjusted numbers.

It is interesting that the graduation rate for the Other race group is omitted from the main paper and the Supplementary Material Table S3, because by my calculations, in Colorado, the Other graduation rate decreased after the CFPI contraception access expansion, but in the Parallel Trends states (the main comparison group of US states that the authors use), the Other graduation rate increased significantly. The one missing row in the Table is exactly the one in which the results are the opposite to the rest of the paper and the conclusions of the authors.

University incentives not to punish cheating

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Universities have incentives not to expel cheaters, because these students would stop paying fees. By extension, there is a motive to avoid punishing academic dishonesty in any way that increases the chance of the student dropping out, like giving a cheater a failing grade. The university then gives a similar incentive not to punish academic dishonesty to its departments, who then pass on these incentives to faculty. In every university I have been in, it is far easier for a faculty member to do nothing about cheating – it requires no work, as opposed to a lot of bureaucracy documenting the cheating, imposing the punishment, dealing with the appeals, etc. There is no punishment for a faculty member who fails to report cheating, but to be fair, also no punishment for a false accusation of cheating, or an accusation that does not have sufficient evidence or gets overturned on appeal.

Even if a faculty member tries to punish academic dishonesty, the cheating student appeals to the university hierarchy and the higher-ups overturn the punishment. If not the first level of the hierarchy, then one of the higher levels. Thus even an inherently honest professor who for psychological reasons would be willing to spend the time to document academic dishonesty if it led to the cheater getting punished does not do so, because in the end there is no punishment.

A solution is to change university incentives: the students who are expelled because of cheating must pay their fees in full for their entire course of studies. A problem is that this leads to legal challenges because the student is not getting the education service but must pay for it. One solution is to require the tuition paid up front, non-refundable on expulsion for cheating. However, in this case students have to take a loan (which may be prevented by credit constraints or risk aversion) and may instead choose universities that do not charge them up front.

The university-side incentives also seem problematic if tuition is fully paid for expelled cheaters, because the university could save on the teaching costs by kicking out all the students on fabricated charges and keep the money. The long-term reputation cost for the university prevents such rip-offs.

A milder way to improve the university incentives is to require the cheater to re-take the course. This may delay the time at which the cheater can take follow-up courses that have the re-taken course as a prerequisite. The resulting delay in graduation may require the cheater to pay extra fees for the additional time, but the extra payment of course depends on the specific regulations of the university.

Preventing cheating is hopeless in online learning

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Technology makes cheating easy even in in-person exams with invigilators next to the test-taker. For example, in-ear wireless headphones not visible externally can play a loop recording of the most important concepts of the tested material. A development of this idea is to use a hidden camera in the test-takers glasses or pen to send the exam contents to a helper who looks up the answers and transmits the spoken solutions via the headphones. Without a helper, sophisticated programming is needed: the image of the exam from the hidden camera is sent to a text-recognition (OCR) program, which pipes it to a web search or an online solver such as Wolfram Alpha, then uses a text-to-speech program to speak the results into the headphones.

A small screen on the inside of the glasses would be visible to a nearby invigilator, so is a risky way to transmit solutions. A small projector in the glasses could in theory display a cheat sheet right into the eye. The reflection from the eye would be small and difficult to detect even looking into the eyes of the test-taker, which are mostly pointed down at the exam.

If the testing is remote, then the test-taker could manipulate the cameras through which the invigilators watch, so that images of cheat sheets are replaced with the background and the sound of helpers saying answers is removed. The sound is easy to remove with a microphone near the mouth of the helper, the input of which is subtracted from the input of the computer webcam. A more sophisticated array of microphones feeding sound into small speakers near the web camera’s microphone can be used to subtract a particular voice from the web camera’s stereo microphone’s input. The technology is the same as in noise-cancelling headphones.

Replacing parts of images is doable even if the camera and its software are provided by the examiners and completely non-manipulable. The invigilators’ camera can be pointed at a screen which displays an already-edited video of the test-taker. The editing is fast enough to make it nearly real-time. The idea of the edited video is the same as in old crime movies where a photo of an empty room is stuck in front of a stationary security camera. Then the guard sees the empty room on the monitor no matter what actually goes on in the room.

There is probably a way to make part of the scene invisible to a camera even with 19th century technology, namely the Pepper’s Ghost illusion with a two-way mirror. The edges of the mirror have to be hidden somehow.

Training programs should be hands-on and use the scientific method

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The current education and training programs (first aid, fire warden, online systems) in universities just take the form of people sitting in a room passively watching a video or listening to a talk. A better way would be to interactively involve the trainees, because active learning makes people understand faster and remember longer. Hands-on exercises in first aid or firefighting are also more interesting and useful.

At a minimum, the knowledge of the trainees should be tested, in as realistic a way as possible (using hands-on practical exercises). The test should use the scientific method to avoid bias: the examiner should be unconnected to the training provider. The trainer should not know the specific questions of the exam in advance (to prevent “teaching to the test”), only the general required knowledge. Such independent examination permits assessing the quality of the training in addition to the knowledge of the trainees. Double-blind testing is easiest if the goal of the training (the knowledge hoped for) is well defined (procedures, checklists, facts, mathematical solutions).

One problem is how to motivate the trainees to make an effort in the test. For example, in university lectures and tutorials, students do not try to solve the exercises, despite this being a requirement. Instead, they wait for the answers to be posted. One way to incentivise effort is to create competition by publicly revealing the test results.

Distinguishing discrimination in admissions from the opposite discrimination in grading

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There are at least two potential explanations for why students from group A get a statistically significantly higher average grade in the same course than those from group B. The first is discrimination against A in admissions: if members of A face a stricter ability cutoff to be accepted at the institution, then conditional on being accepted, they have higher average ability. One form of a stricter ability cutoff is requiring a higher score from members of A, provided admissions test scores are positively correlated with ability.

The second explanation is discrimination in favour of group A in grading: students from A are given better grades for the same work. To distinguish this from admissions discrimination against A, one way is to compare the relative grades of groups A and B across courses. If the difference in average grades is due to ability, then it should be quite stable across courses, compared to a difference coming from grading standards, which varies with each grader’s bias for A.

Of course, there is no clear line how much the relative grades of group A vary across courses under grading discrimination, as opposed to admissions bias. Only statistical conclusions can be drawn about the relative importance of the two opposing mechanisms driving the grade difference. The distinction is more difficult to make when there is a „cartel” in grading discrimination, so that all graders try to boost group A by the same amount, i.e. to minimise the variance in the advantage given to A. Conscious avoidance of detection could be one reason to reduce the dispersion in the relative grade improvement of A.

Another complication when trying to distinguish the causes of the grade difference is that ability may affect performance differentially across courses. An extreme case is if the same trait improves outcomes in one course, but worsens them in another, for example lateral thinking is beneficial in a creative course, but may harm performance when the main requirement is to follow rules and procedures. To better distinguish the types of discrimination, the variation in the group difference in average grades should be compared across similar courses. The ability-based explanation results in more similar grade differences between more closely related courses. Again, if graders in similar courses vary less in their bias than graders in unrelated fields, then distinguishing the types of discrimination is more difficult.

The obsolete PhD degree

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Let’s distinguish the knowledge from the degree first. The average skill requirement of jobs (measured in years of education for example) is rising over time, so people need more knowledge before entering the labour market. What is obsolete is the packaging of that knowledge into degrees and perhaps its teaching in universities.
The PhD takes six years on average (http://gsa.yale.edu/sites/default/files/Improving%20Graduate%20Education%20at%20Yale%20University.pdf) and during that time the student is guided by one or at most a few advisors. Working on the same topic on years is often necessary to become an expert, so unavoidable. But being tied to the same advisor is a throwback to the medieval guild system where the apprentice and journeyman work years for the master. It means seeing only one viewpoint or set of techniques. Most importantly, the topic of the thesis is limited to what the advisor is competent in (sometimes a laissez-faire advisor allows a dissertation on an unfamiliar subject, which is even worse – incompetent advising follows). Taking courses from other faculty in the same department or university broadens the horizons a bit, but there may be an institutional culture that introduces biases, or expertise in some fields may simply be missing from the university. Attending conferences again broadens the mind, but conferences are few and far between. Suggestions that run counter to the advisor’s views may be interpreted as wrong by a novice graduate student.
Ideally, a trainee researcher would be advised by the whole world’s scientific community, mostly but not exclusively by people in the same discipline. Electronic communication makes this easy. Many different viewpoints would be explained to the graduate student, interpersonal issues would be easier to resolve by changing advisors (no lock-in to one person who determines one’s career prospects). People who just use students as free labour without providing much in return would suddenly become lonely. The problem is moral hazard – if no specific person has responsibility for a student, indefinite postponement of advising effort may occur. Credit for useful advice would be spread between many people, which dilutes incentives. In short, advising is a public good.
Still, public goods are sometimes provided, despite the difficulty of explaining this with a rational agent model. People write free software, answer questions from strangers in forums, upload advice and instructions on many topics. This suggests some volunteer advisors would step forward under a shared responsibility system. The advisor pool may become more ideologically biased than now, because people who want to spread propaganda on their strong views have a greater incentive to volunteer advice. They do this on the internet, after all. Similar incentives for shrill prophets operate in universities, but if each faculty member is required to advise some students or if there is a cap on how many disciples one can take, there is less scope for indoctrinating the masses. Such restrictions can be imposed online to some extent. There could be a reputation mechanism among the advisors, so the crackpots are labelled as such. The larger pool of opinions may balance the biases.
The economies of scale in advising one student are reduced with sharing. A single advisor per student means that during most of the PhD program, the advisor is already familiar with the student’s work and only needs to read the new part each week. With many advisors, each would need to devote time to the same material. Some sharing of responsibilities (one reads the introduction, another the conclusion) is possible, but the interdependence of the parts of the research does not permit full splitting.
Another medieval aspect of the PhD is paying for the received teaching in labour, not money. Graduate students may be free from tuition and may even get a scholarship, but in return have to work as teaching assistants or do the advisor’s research in their lab. Less ethical help also occurs, such as reviewing papers the advisor is officially the referee of. Inefficiencies of a barter economy are introduced. Instead of paying for the program with money earned in the job the student is the most productive or happy in, the student is forced to work as a teaching assistant and essentially pay the difference between a fair market wage and the teaching assistant wage to the university. Further, the teaching work is restricted to the university of the PhD program, even if other universities need teachers more and offer higher wages. This gives the university market power and allows it to depress grad student salaries.
A doctoral program may lose money directly, in the sense that teaching the grad students is more expensive (due to small classes, advanced material, so more professor time per student) than their TA work. The fact that universities still keep the PhD programs suggests the existence of indirect benefits. One is reputation – attracting paying undergraduate and Master’s students. In some countries, an institution is not allowed to call itself a university if it does not teach at the doctoral level. Altruism by the higher education sector is possible, even if John Quiggin’s quote “never stand between a Vice-Chancellor and a bucket of money” suggests otherwise.
One utopic proposal is an online system where graduate students and advisors sign up and can talk over video calls, send emails etc. It keeps a record who communicated with whom and how much. Later, data on the academic achievement and job market performance of students can be added, so advisors can be rewarded for their students’ success. There may also be some popularity index, meaning students rate their advisors and vice versa. But in the end, an advisor’s contribution should matter more than popularity, so the latter is optional. Advisors may look at and rate each other’s advising sessions to limit the spread of bad advice. Students can collaborate and may decide to meet in person.
For experimental science, lab space can be rented by student cooperatives. Instruction in the use of equipment can be given via video. Classroom space can also be rented directly by groups of students if needed. The students may pay advisors. Some people may only advise conditional on payment. Students may teach other students (including TA jobs), whether for money or pro bono. The system would cut out the middlemen – university administrators – making education cheaper for society. Of course, in the lab and classroom rental business, other middlemen would appear and take their share.

Ideas for popular science experiments

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There are many science fair experiment ideas online. The following may be repetitions.
A windmill connected to an electric generator, which is connected to a lightbulb (small dimmable is best). Blow on the windmill to turn the light on. A separate generator similar to the one attached to the windmill, which can be cranked by hand to turn on the lightbulb. An electric fan that can blow on the windmill, with power consumption at the fan and power production at the windmill measured and displayed. This explains efficiency losses in power generation.
Pressure of light. A piece of paper attached vertically on a platform that can rotate at low friction. On one side of the rotation axis, the paper is painted black, on the other, it is white. Reversed on the opposite side of the paper. Transparent dome over the setup to prevent air currents interfering. Shining a light on the paper makes it rotate, because the pressure on one side is greater. The rotating platform can be a polystyrene disk floating in water.
Pulleys and gear ratios. A bicycle with gears, rear wheel removed, but axle in place. Rope attached to axle, weight to rope. Rotating the pedals lifts the weight. Different gears require different number of rotations to lift the weight to a given height, but the more rotations needed, the less force needed for the rotation. Explain why low gears on a bike should be used when starting and on uphills, but high gears on downhills.
Moving pulleys: the distance the rope has to be pulled becomes longer, but the force required to pull becomes smaller to lift a given weight a given distance.
Friction in braking. Several bicycle wheels with brakes attached. Some rims are dry, some wet, some oiled. Feel the braking force required to stop each. To provide the force that the brakes must counter, a weight can be attached to each wheel. Rotate the weight away from the lowest point of the wheel and try to use the brakes to prevent the weight from sinking to the bottom again.
Friction in accelerating. Old bicycle. Rotate the pedals to accelerate the rear wheel to a given speed (measured with a bicycle speedometer) when the chain is dry, or oiled, or sand is poured on the chain. Feel the different difficulty depending on the condition of the chain. Several bikes is better, so the chains in different condition can be compared.
Friction and heat: a fire drill. Rotate a sharp stick in a hole in a piece of wood – the hole blackens and starts to smoke.
Ball bearings. Stack two blocks, put weight on the top one, try to rotate the bottom one. Now the same blocks with two ball bearings, one between the ground and the bottom bearing and the other between the two blocks. Much easier to rotate the bottom block. Explain how rolling friction is smaller than dragging friction. Friction proportional to pressure. Friction related to surface area.
Tire pressure and friction. Bicycle wheels (preferably with identical rims, hubs and spokes) with different width tires on them. Measure the friction of the tires by the force required to rotate them at a given speed on some surface, with the tire bearing weight. A stationary bicycle trainer can be used. Which tire width gives the lowest friction? Research shows that 22-23 mm tires have the lowest friction under the weight of an adult cyclist. Deflate the tire, measure the friction. Inflate, measure the friction. Which inflation pressure gives the lowest friction? Research shows that it is not the maximal pressure, unless the surface on which the wheel rotates is very smooth.
Mining and ores. Different rock samples of various ores. Panning for “gold”: try to find a shiny grain hidden in a quantity of mud or sand.
Solvents. Pebbles or small toys mixed in sugar paste or syrup, which is then dried into blocks. Use water to dissolve the sugar and discover what is inside the blocks.
Leidenfrost effect. Air hockey table with air being pumped under the hockey puck. Compare to droplets of liquid nitrogen rolling on a warm surface. Compare to pancakes riding on the steam bubbles under them on a hot pan.
Bridge of spaghetti. Dry spaghetti can be attached to each other with small balls of dough (flour mixed with water). Then bake the spaghetti-and-dough construction to harden the dough. Check how much weight the bridge can carry. Compare the breaking weight for a bridge (triangularly connected spaghetti that look like high-voltage power line towers) to the breaking weight for a bunch of horizontal spaghetti. The bridge can also be made by glueing matches or toothpicks.
Detergents. Lightly grease some cloth that normally absorbs water. Put water on top of that cloth – droplets form and nothing leaks through. Put water in a cloth bag and show that it does not leak. Compare to ungreased cloth that lets water through. Add detergent to the water on the greasy cloth. With the right coarseness of cloth, amount of grease and detergent, the water should start leaking through.
A burner under a thin paper box filled with water. The paper does not burn and does not become soggy, so the water does not leak through.
Absorption and radiation. Heat lamp shining on a black and white rock. Which becomes warm first? Now heat the rocks by contact, e.g. in warm water. Which rock cools down first? Infrared laser thermometer may help confirm temperatures. Or an ordinary thermometer inserted in a hole drilled in the rock.
Hot air rises. A nonflammable parachute rises above a candle. The parachute could be of thin tinfoil. It should have a light weight attached below the canopy to keep it upright. A tinfoil pinwheel can be held above the candle – it starts to rotate in the updraft of hot air.
3D printing by hand. Mud dripped from a hand onto sand or another surface that lets water through easily. The water soaks out of the droplets of mud that hit the surface, leaving a series of solid bumps of mud. Drop another droplet of mud on top of the bumps – water soaks out again, the bumps are now higher. Use this technique to build walls, castles etc.
Internal combustion engine. A rotating shaft with two pistons attached (can be made of wood or some other cheap, light, strong enough material). A balloon under each piston. If two people rapidly inflate and let deflate the balloons in the right sequence, then the shaft starts to rotate. Also a great party game – which couple gets their motor running fastest? The balloons can also be inflated by a hand pump, but fast and well-timed deflation is then a problem. One end of a long snakelike balloon can be under the piston, the other end squeezed and released by hand. The right sequence of squeeze and release can make the shaft rotate. One person can hold two long balloons, so can rotate the engine alone. A single piston is enough to rotate a wheel if attached to the rim – this is the arrangement in some old steam locomotives and foot-pedalled Singer sewing machines.
Steam power. Electric kettle boiling water, with a small windmill above the spout. The steam rising from the kettle rotates the windmill. Measure the power generated by the windmill and compare to the electricity required to heat the kettle.
Electric motor. Hand generator produces electricity, which is led by wires to an electric motor, which starts to rotate. Or the electricity is led to a coil with a permanent magnet inside. The magnet starts to move when the hand generator is cranked. With the right speed of cranking, an alternating current can make the magnet rotate.
Water mill. Pour the water at the top of a halfpipe. A waterwheel in the halfpipe starts to rotate in the flow. The rotation can drive a small generator which lights up a tiny lightbulb.
Archimedes’ screw. A helix in a pipe that is slightly tilted from horizontal can be rotated to pump water up the pipe.
Connected vessels. Two cups of water at different heights linked by a bent drinking straw. Suck the bottom of the straw to get water over the hump in the straw. Then water will start to flow from the top cup to the bottom, initially going uphill in the straw.
A bit of charcoal dropped in a vial of pure oxygen spontaneously catches fire. The oxygen can be generated at the bottom of the vial using hydrogen peroxide and a drop of blood. Steel wire in a pure oxygen environment rusts rapidly enough to be observed in a single experiment.
Bimetal thermostat. Two strips of different metals glued, soldered or riveted together at the ends. Heat the joined strip with a hair dryer – it bends to one side. The bent strip can touch a contact and switch something on or off, for example the hair dryer. A feedback loop can be constructed: if the joined metal strip gets cold enough, then it switches on the hair dryer, which heats the strip, which then switches off the hair dryer.
Tracks vs wheels. Tracked and wheeled model vehicles driving in a sandbox and on a smooth surface. The vehicles are the same weight, have the same motor and battery. Compare performance going up a sandhill vs racing on a smooth surface.
A spinning top to illustrate gyroscopes and self-stabilising.
Degrees of freedom of movement. Mechanical devices that illustrate the 3 translation and 3 rotation possibilities by allowing some of them, but not others. For example the serial gimbal, 3-axis gimbal, origami for thick materials (Science 24 Jul 2015: Vol. 349, Issue 6246, pp. 396-400, DOI: 10.1126/science.aab2870), bicycle front fork with shock absorbers, shopping trolley wheel or office chair wheel. For fun, rotate a person on an office chair a few dozen turns, then ask them to walk in a straight line.
Origami: Miura fold, hexaflexagon. Cutting and gluing mathematical objects, e.g. a Mobius strip, a Klein bottle. Math drawing with compass and ruler, e.g. a flower made from 7 interlinked circles of the same diameter. Sierpinsky carpet. Inscribing circles in squares and vice versa.
Boil amaranth in a transparent vessel. The grains dance on the bottom, then form columns, then a goo with large breaking and splattering bubbles.
Water volcano. A small bottle of warm coloured water is dropped in a large transparent vessel containing clear cold water. The coloured water will rise to the top and spread out, like a volcanic ash plume rises in the atmosphere and spreads in a layer.
Twinkling stars and heat mirages. A transparent rectangular vessel of water with points of light behind it. Look through the water: the points do not move. Now heat the water from the bottom: the points of light start to wobble, because warm water currents are rising up and bending the light passing through them.
Refractive index measurement. Water and cooking oil in transparent vessels. One person puts a straight stick at an angle into the liquid – the stick seems to bend at the immersion point. The person points out where they perceive the bottom end of the stick to be. Another person at the side of the vessel measures the angle between the perceived and actual sticks. The difference in angles is different for water than for oil.
Muscles and joints. Ask a person to relax their hand on a table, palm up. Press on the inside forearm and pull it toward the elbow – the 3 smallest fingers bend. Pull the palm towards the wrist – the fingers bend. An excavator’s scoop is moved by pistons like human limbs are moved by muscles – by pulling on the joint on one side or another.
Centrifuge to separate liquids, or solids from a liquid. The low-cost whirligig centrifuge (paperfuge) is described in Nature Biomedical Engineering 1, Article number: 0009 (2017) doi:10.1038/s41551-016-0009 and http://www.nature.com/news/spinning-toy-reinvented-as-low-tech-centrifuge-1.21273 Animal blood or some mixture of liquids and solid flakes can be separated into component liquids and solids by spinning it.
Solar-powered distillation. The 1 square metre device made of polystyrene, paper and charcoal distils about 1 litre of water per hour, as described in http://www.sciencemag.org/news/2017/02/sunlight-powered-purifier-could-clean-water-impoverished Explain capillary action, evaporation and condensation, black material absorbing heat radiation faster.
Passive cooling. Glass beads 8 micrometres in diameter embedded in a polymethylpentene film backed with a thin silver film. The film conducts heat from the surface it sits on and radiates it away in in the other direction. http://www.sciencemag.org/news/2017/02/cheap-plastic-film-cools-whatever-it-touches-10-c
Oil- and water-repellent coating of glass. Cannot be prepared on the spot, but previously fabricated coatings can be demonstrated. Deposit candle soot on glass, then coat with a 25 nanometre silica film by putting the glass in a desiccator with open vessels of tetraethoxysilane and ammonia for 24 hours. Heat to 600C in air for 2 hours. Put in a desiccator with open beaker of semifluorinated silane for 3 hours. Xu Deng et al. “Candle Soot as a Template for a Transparent Robust Superamphiphobic Coating” http://science.sciencemag.org/content/sci/335/6064/67.full.pdf?sid=ca40c018-0715-4d3b-8e36-58c329dea347

Electricity and water analogy. Pouring water down an inclined halfpipe to rotate a water wheel under the bottom of the halfpipe. The water wheel is connected to a winch that can lift a small weight. The height or angle of the halfpipe and the quantity of water can be changed, which lifts the weight at different speeds or can lift a larger weight. The height of the halfpipe is analogous to the potential difference (voltage) and the quantity of water per second to the current (amperage, electrons per second). The water wheel can also be connected to a generator that powers a small dimmable lightbulb. The brightness of the bulb changes with the speed of the water wheel.
Plastic beads in water poured down a halfpipe can demonstrate the measurement of flow per unit of time: the number of beads passing a given point per ten seconds for example.
Ship shape. Make model boat hulls out of some easily worked material, e.g. putty, model clay (hull must be thin to float), cut styrofoam, cardboard taped together and covered with cling film. The styrofoam needs extra weight, for example a piece of sheetmetal pushed through it in the middle to make a keel. The cardboard boat can carry some gravel as ballast. Then each boat gets a motor of equal power, e.g. a propeller powered by a wind-up spring from some toy. Weigh the boats and add ballast as needed to equalise weights. Race the boats to see which hull shape is fastest. To keep the racing boats straight, put them in parallel halfpipes of water, or create swimming pool lanes in a large tub by parallel strings drawn taut on the surface of the water.

Priming the pump. An interesting mechanical device is a piston pump for getting water out of the ground. A piston moves up and down in a vertical pipe open at the top. There is a hole in the side of the pipe from which water can come out. The piston passes above and below the hole as it moves. A dry piston doesn’t pump water up, but pouring some water on the piston (priming the pump) creates a temporary airtight seal around the piston, so pulling the piston up creates a slight vacuum under it, which draws the water up. The water flows out of the hole in the side of the pipe.
Spinning methods and yarn properties. Threads or wires can be spun into yarn by cone spinning, Fermat or dual-Archimedean spinning. With enough twist, the yarn starts to coil like a telephone cord. Folding twisted yarn in two makes the two halves twist around each other – this is how rope is made. Twisted but uncoiled yarn can be coiled in the opposite direction to the twist. Removing the core around which the coiling took place lets the twist and coil cancel – parallel threads result.

Ricequakes as a model of rockfill dam collapse: put puffed rice in a transparent vertical vessel under pressure and let water in from the bottom. The rice starts compacting in sudden collapses, not gradually. Itai Einav and François Guillard “Tracking time with ricequakes in partially soaked brittle porous media” http://advances.sciencemag.org/content/4/10/eaat6961

Capturing water vapour in water beads flowing down vertical cotton threads while the humid air flows up along the threads. The goal is desalination and water purification in general. A Sadeghpour et al 2019 https://advances.sciencemag.org/content/5/4/eaav7662

Soft pneumatic oscillator driven by constant pressure: three cylinders connected a ring, each containing a bistable hemispherical diaphragm. The diaphragm popping to the other side buckles a tube, choking airflow to the next cylinder, which allows its diaphragm to pop back, straightening a tube and allowing airflow. Preston et al. 2019 https://robotics.sciencemag.org/content/4/31/eaaw5496

Blind taste test: compare premium food brands to cheap ones, organic to non-organic, farmers’ market and supermarket produce, fake crabmeat or grape juice to real, different sorts of apples or other fruits, nuts, vegetables, mushrooms. The testers could be blindfolded and audio-record their observations. For written observations, testers could close their eyes while assistants put food pieces in their mouths, then open their eyes for writing. The food pieces should be numbered in advance.

Blind clothing test: compare the warmth of socks, hats, gloves, scarves, the feel of different fabrics. An assistant puts the garment on the blindfolded tester who then audio-records the observations about the feel.

Soft phototactic swimmer based on self-sustained hydrogel oscillator: a hydrogel plate floats on water, has an underwater tail of hydrogel with embedded Au nanoparticles. Light shone on the tail heats the particles, heat bends the tail. The tip of the tail then casts a shadow on the previously illuminated part, which cools and straightens it. Straightening removes the shadow, letting light bend the tail again. Constant light thus causes the tail to oscillate, which propels the swimer away from light. Zhao et al. 2019 https://robotics.sciencemag.org/content/4/33/eaax7112

Delta wing carbon fibre robot launched from water to air by exploding acetylene, then gliding back to water. The explosion forces a water jet out from the reaction chamber through a nozzle. Acetylene produced on board from calcium carbide powder and water. Zufferey et al. 2019 https://robotics.sciencemag.org/content/4/34/eaax7330

Magnetic quadrupoles as building blocks for stable complex shapes. The quadrupoles are made from two magnets placed at a 20-degree angle to each other in a 3D printed square case. Joining the cases with an elastic stick allows the assembly to deform interestingly under magnetic fields. Gu et al. 2019 https://robotics.sciencemag.org/content/4/35/eaax8977

Objects float on the underside of viscous silicon oil or glycerol that is suspended above air using >100Hz vertical vibration. Apffel et al 2020 https://www.nature.com/articles/s41586-020-2643-8

Grooves in a material that swells in water or some other solvent make it bend as thinner parts of the material absorb water faster. Grooved flat pasta dough can be made to take 3D shapes when boiled. Tao et al 2021 https://advances.sciencemag.org/content/7/19/eabf4098

Teaching and research and division of labour

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Universities usually prefer that the same person both teaches and does research. There are some purely teaching or purely research-focussed positions, but these are a minority. Both teaching and research achievements (and service as well) are required for tenure. This runs counter to Adam Smith’s argument that division of labour raises overall productivity. One possible cause is an economy of scope (synergy), meaning that teaching helps with research, or research helps to teach. In my experience, there is no such synergy, except maybe in high-level doctoral courses that focus exclusively on recent research. Revising old and basic knowledge by teaching it does not help generate novel insights about recent discoveries. Complex research does not help explain introductory ideas simply and clearly to beginners.

Another explanation is that universities try to hide their cross-subsidy going from teaching to research. The government gives money mainly for teaching, and if teachers and researchers were different people, then it would be easy for the government to check how much money was spent on each group. If, however, the same person is engaged in both activities, then the university can claim that most of the person’s time is spent teaching, or that their research is really designed to improve their teaching. In reality, teaching may be a minor side job and most of the salary may be paid for the research. This is suggested by the weight of research in hiring and tenuring.

The income of universities mostly comes from teaching, so they try to reduce competition from non-university teachers and institutions. One way is to differentiate their product by claiming that university teaching is special, complicated and research-based, so must be done by PhD holders or at least graduate students. Then schoolteachers for example would be excluded from providing this service. Actually the material up to and including first year doctorate courses is textbook-based and thus cannot consist of very recent discoveries. With the help of a textbook, many people could teach it – research is not required, only knowing the material thoroughly. For example, an undergraduate with good teaching skills who was top of the class in a course could teach that course next semester. Teaching skill is not highly correlated with research skill. The advantage someone who recently learned the material has in teaching it is that they remember which parts were difficult. A person who has known something for a long time probably does not recall how they would have preferred it taught when they first learned it.

Researchers forget the basics over time, because they rarely use these – there are more advanced methods. The foundations are learned to facilitate later learning of intermediate knowledge, which in turn helps with more complicated things and so on up to research level. Similarly in sports, musical performance, sewing, the initial exercises for learners can be quite different from the activity that is the end goal. A sports coach is rarely an Olympic athlete at the same time, so why should a teacher be a researcher simultaneously?

On electric bikes and science news

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There is some debate on whether electric-assist bikes are good or bad. The argument on the negative side is that people will stop cycling and bike roads will be taken over by these (electric-)motorized vehicles. On the positive side, the claim is that electric bikes replace motor scooters, cars and public transit, which is good for the environment and perhaps health if people actually pedal their electric bike a bit. To summarize: electric bikes good if replace motor vehicles, electric bikes bad if replace bicycles or walking. It is an empirical question what the substitution sizes are.

There are many calls for scientists to communicate better, engage the public, present their results simply and interestingly etc. Whether more science news and popular science is good or bad depends on what it replaces, just like for electric bikes. If dumbed down entertainment science replaces the rigorous variety, this is bad. If science news replaces brainless news (celebrity gossip, funny animals, speculation on future events), it is good. It is an empirical question to what extent scientists switch to popular topics and crafting press releases if their evaluations rely more on outreach or policy impact. Also a question for the data is which news are left out of print to make room for more science news.

To maximize education of the public, there is a tradeoff between the seriousness of the science presented and the size of the audience. Research article level complexity is accessible to only a few experts. Entertainment is watched by many, but does not educate. The optimum must be somewhere in the middle.

Similarly, difficult courses in a university have few students taking them, but teach those few more than fun and easy subjects. The best complexity level is somewhere between standup comedy and a research seminar.