Editor's pick: Hey teacher! Leave those kids alone!
Your interview with Sugatra Mitra about children learning for themselves was fascinating (3 November, p 42). It chimed very well with research I did for a master's in education in 1989, on the role children wanted the teacher to play during group work. The 8-year-olds' conclusions were that the teacher should keep order, help with spelling, and wait to be invited into the group when needed for information.
One child said: “I like working in groups because you can discuss things and get other people's suggestions. I think the teacher should be sitting at their desk in case you need them. I don't like teachers interfering with what you are talking about.”
This research altered my classroom practice for the better – until top-down pressure squeezed this method out of the curriculum in favour of more testable routine. The surest way to develop potential in all children, regardless of their background and opportunities for education, is still independent learning. Natural curiosity and enthusiasm to know will stimulate a life long desire to learn.
What to do with a huge mass of binned clothes? (1)
Alice Klein describes how clothes are “recycled” into flat panels (10 November, p 10). Work to reduce our waste is admirable, but this seems to me a misguided approach: downcycling the waste rather than recycling.
Blending materials together removes any possibility of further recycling. The materials are still ultimately likely to end up in landfill. Wouldn't it be better to separate the clothes by material and try to make something that takes advantage of the original properties of each material?
What to do with a huge mass of binned clothes? (2)
You say that 10 million tonnes of landfill is generated from binned clothes in the US alone every year. Given a population of around 325 million, that is an average of 30.8 kilograms of clothes thrown away per person, per year: 68 pairs of jeans or 616 socks. Is this statistic pants?
The editor writes:
• It is a startling figure, from . Most of the 10 million tonnes of textiles comprises discarded clothing. Smaller sources include furniture, carpets, tyres, footwear, sheets and towels.
First class post 鈥� 8 December 2018
There are two ways this can end: badly and expensively. OK, just the one way
@undeadbydawn to use AI to predict whether individuals will commit violent crime (1 December, p 6)
How climate change combat can start at home (1)
Your article on home heating made important and compelling reading (17 November, p 22). The UK is adding to its vast supply of older, inefficient buildings with new-build homes that are still the least efficient in Europe: 90 per cent of the homes the country will have in 2050 have now been built, and they are all carbon-hungry.
All that Michael Le Page says about retrofitting insulation as a solution is that it is costly. In 2011, I bought a neglected stone house built in the 1880s: comprehensive insulation and draught proofing have reduced the annual heating energy load by 75 per cent. The refurbishment was expensive, but the insulation itself cost £6000 – less than many people spend on a kitchen refit. Crucially, though, while I use natural gas for heating now, the building is much more suited to alternative heating sources in the future.
We do need both demand management, for example through smart pricing, and alternative supply, but insulation must be the first priority. It can be done one building at a time, rather than requiring big projects.
How climate change combat can start at home (2)
Everyone has a part to play in combating climate change, and changing expectations is part of this alongside new heating systems. Since central heating became commonplace in UK homes around 40 years ago, people have become used to their homes being warm as soon as they get home. The warmer their homes are in winter, the less likely they are to turn their heating off in spring.
How climate change combat can start at home (3)
I enjoyed the article on home heating and climate change, as someone who fitted a ground-source heat pump to my home well before the UK's or any other renewable energy subsidies were developed. You note that UK peak demand for heat energy in the winter is six times higher than that for electricity, implying that much heat demand cannot be met by electricity from renewables.
But if, for example, all heat energy were supplied by heat pumps producing five times as much heat energy as they use in electrical energy, this difference would be lower. This would indicate the full benefit of using heat pumps – provided we drive them from renewable sources.
The roots of the study of plant sentience
I look forward to reading Monica Gagliano's book , and wish her the very best of success (24 November, p 40). Research into plant sentience has a patchy but interesting and important history.
The first work devoted to it that I know of was a 1688 doctoral dissertation attributed to Johannes Mauchartus, the (“Botanical disquisition on the Mimosa or Sentient Plant”). The main author of this was probably Rudolph Jacob Camerarius, his supervisor, whose experiments decisively proved the presence of reproduction by sexual means in flowering plants.
Serious popular literature includes Daniel Chamovitz's 2012 and Dov Koller's 2011 . My favourite, which deals with many other subjects as well, remains Rodolfo Llinás's I of the Vortex: From neurons to self (reviewed 25 August 2001, p 52). Llinás discusses tunicates (sea squirts) some of which start life as free-swimming larvae with a rudimentary nervous system.
Once settled, these larvae digest most of their rudimentary brain and live more or less like a plant. The need to handle irregular movement in an extended space in the first stage but not the second may explain the probable original function of a sizeable part of the early brain.
Do close-in planets survive solar winds?
Ryan MacDonald notes that in the early 1990s Michel Mayor and Didier Queloz were the first to observe an exoplanet around a sun-like star (10 November, p 38). It was thought to be a gaseous “hot Jupiter” orbiting eight times closer to its star, 51 Pegasi, than Mercury is from the sun.
Rocky planets are thought to have formed with gaseous mantles. These were then stripped away by an outflux of particles from their star – called a “” after the star for which a class of young stars is named – during their solar system's infancy. If this is correct, how did the hot Jupiter close to 51 Pegasi avoid a similar fate? If it is wrong, could the rocky planets and the cores of the sun and Jovian planets (before they acquired their gas mantles) have been nomadic interstellar interlopers (17 November, p 19)?
The climate impact of more electric cars
Paul Barnfather correctly says that the average carbon footprint of UK electricity generation is falling due to the increasing proportion of renewable energy (Letters, 10 November). But existing low-carbon generation is already at or near its maximum capacity, so a large increase in the numbers of electric vehicles will represent an additional demand that will normally be met by burning fossil fuels; at best gas, at worst coal.
This will continue until renewable capacity comes online to meet additional demand, or we can store its spare output in large-scale facilities.
Another method of reducing pollution compared with burning petrol or diesel is to burn liquefied petroleum gas directly in internal combustion engines. Existing vehicles can be converted and won't suffer the limited range and slow refuelling of electric vehicles. It may not be what we should aspire to, but surely is a useful intermediate step?
The editor writes:
• A lot depends on long-term policy to build more renewable capacity. is to use the cars themselves as storage, starting with “smart charging” when renewable generation is at its highest.
Another argument for Dorothy Hodgkin
I agree with Alice Bell's support for Dorothy Hodgkin to be on the new UK £50 note (10 November, p 24). Another aspect of her career is that she attended a state school, whereas each of the other 20th-century candidates mentioned – Rosalind Franklin, Alan Turing and Stephen Hawking – went to private schools. Mentioning this could show children in state schools that they have as much chance of getting on in science as anyone else – I hope.
When the odds on a DNA match are deadly serious
A man was apparently declared dead because DNA from a decomposed corpse was 99.92 per cent likely to be his (Feedback, 17 November). When he turned up alive we were reminded to think of the 0.08 per cent. So should a jury in a murder trial be persuaded of a suspect's guilt by a similar likelihood?
Quick – observe a short-lived radio burst now!
Ray Vickers seeks a more accurate word for the F of “FRB” (Letters, 24 November). Have his efforts in this direction been too… fleeting?
The editor writes:
• Three other readers had suggested this as we went to press.
For the record 鈥� 8 December 2018
鈥� The film Anthropocene includes a scene of vast fields of lithium ore drying in the sun (17 November, p 45).
鈥� These eggs aren’t so large: a human ovum is about 0.1 millimetre across (24 November, p 28).