Do try this at home? Science experiments as homework
Teachers say science experiments are disappearing from schools. But that doesn't have to mean the end of the Van der Graaf generator
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Your support makes all the difference.Science experiments in schools are fast becoming a thing of the past, according to the teachers who feel compelled to sideline them. The pressures from an overloaded curriculum, a lack of funding and poor behaviour by pupils has led to the vast majority of science teachers cutting down on practical work.
Chemistry experiments in which teenagers gleefully burn off their eyebrows have been under threat for some years, but other "practicals" have fast become endangered – so much so that professors have drawn up a top 10 list of experiments at risk or absent from many school science labs.
These include the use of ripple tanks to denote wave behaviour, making loudspeakers and electric motors – a link between science and technology – and using geiger counters to denote radioactivity at work.
Almost all of the teachers surveyed (96 per cent) by the national network of Science Learning Centres said there were obstacles which prevented them from undertaking science practicals.
The upshot is that lessons have become more dull, according to Andy Markwick, a science teacher for 25 years. He said the new way of delivering the science curriculum – putting it more into a social context and increasing amounts of assessment – makes teaching core science "like watching paint dry".
"If we want to make more kids go into higher education and take science seriously, that's not going to happen if we teach GCSEs that are dull," added Mr Markwick, of Prendergast Ladywell Fields College in Brockley, south-east London.
Professor John Holman, of the National Science Learning Centre, said: "Learning science without practicals is the equivalent of studying literature without books."
Look and learn: How to experiment at home
By Sofia Mitra-Thakur and Amanda Hall
Van der Graaf generators
What does it show?
Static electricity – the generator uses a moving belt to create a charge imbalance and generate a high voltage on a metal globe, which when touched causes hair to stand on end.
How do you do it?
You can make a Van de Graaf generator at home using an empty drinks can, electrical wires, PVC plumbing pipe, a block of wood, paper cup, fuse and motor. You can also buy a real one online for about £115.
Easiness: 2/5
Safety: 3/5
Fountain experiment
What does it show?
The solubility and acidity/aklalinity of gases.
How do you do it?
Fill a flask with ammonia. Use a syringe to squirt water into the flask, which dissolves some of the gas and forms a vacuum, forcing water from a connected beaker to shoot in and create a fountain.
Easiness: 3/5
Safety: 2.5/5 – ammonia is highly toxic.
Electric motors
What does it show?
How basic electric motors work.
How do you do it?
Using a ferromagnetic screw, one battery cell, a few inches of copper wire, and a neodymium disk magnet, place the screw on top of the magnet and bend the wire. The screw will now have a magnetic charge so it will attach to the button end of the battery. Hold the wire on top of the other end of the battery and lightly touch the other end of the wire on the free end of the battery. The screw will rotate.
Easiness: 5/5
Safety: 4/5
Genetic inheritance
What does it show?
How characteristics are transmitted to offspring.
How do you do it?
By breeding fruit flies together, some with white eyes and others with red eyes, students can find out how eye colour is passed down over generations. You can buy fruit flies online.
Easiness: 3/5
Safety: 4/5
Contact prints
What does it show?
It demonstrates the use of silver salts in photography.
How do you do it?
Silver iodide is passed through filter paper and left to dry. A coin is placed on top and left in the sunlight until the silver salt turns black leaving a negative photographic image under the coin.
Easiness: 3/5
Safety: 4/5
Porous pot diffusion
What does it show?
The diffusion of gases.
How do you do it?
This is a complicated experiment that uses a whole host of lab equipment. Without a ready supply of manometers, some hydrogen and carbon dioxide you'd be a bit stuck.
Easiness: 1/5
Safety: 2/5
Ripple tank
What does it show?
The properties and behaviour of waves – reflection, refraction, diffraction, interference.
How do you do it:
Use a shallow tank of water, lit from above with a lamp, and watch the movement of the water waves.
Easiness: 5/5
Safety: 5/5
Radioactivity detection
What does it show?
Differing levels of radioactivity.
How do you do it?
Use a Geiger counter to measure the radioactive content of ordinary household objects such as salt substitutes. Geiger counters can be bought online for around £90-£100.
Easiness: 5/5
Safety: 4/5
Fermentation
What does it show?
The fermentation process of bread, beer and wine.
How do you do it?
Add yeast to a flask of sugar and warm water, then plug the top. Wait for fermentation to take place, then carefully pour the gas, carbon dioxide, into a boiling tube of limewater, which should go cloudy with the gas. The solution left in the flask is ethanol.
Easiness: 4/5
Safety: 4/5 – as long as you don't drink the pure ethanol, that is.
Electrolytic diffusion
What does it show?
The process of breaking molecules into smaller components using an electricity.
How do you do it?
By directing an electric current through liquid such as molten lead bromide or water using a 12v battery, rods, a beaker and test tubes to catch the gases.
Easiness: 2/5
Safety: 1/5 (You must know exactly what you're doing)
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