Catfood and indigestion cures are the way to spark pupils' interest in science, according to Steven Chapman, a speaker at the Association of Science Education conference.
The head of physics at Oxted school, Surrey, said: "These are science activities which pass the nan test. Children can go home and show them to their nan."
To demonstrate how to give teaching about forces a lift, Dr Chapman plans to launch Alka Seltzer rockets at the conference in Reading tomorrow.
By half filling a film canister with water, dropping in half a tablet of Alka Seltzer and putting the lid back on he will create a build up of carbon dioxide gas.
"Put the canister on a table upside down and it will launch itself into the air and should hit the ceiling," said Dr Chapman. "It's safe, as long as you keep your head out of the way and put paper towels on the floor.
"Although sometimes, instead of launching the canister, the liquid will just bubble out of the side."
Dr Chapman is keen to allay teachers' fears of messing up in front of pupils - or conference audiences.
"There can be more learning going on when things go wrong than when they go right," he said. "Teachers shouldn't worry about it. The main outcome is to get children talking about ideas."
But for the teacher who likes things to go right, he suggests the two tin roll.
"Take a can of soup and a can of catfood, they should be the same size. You are going to roll them down a ramp, ask students to predict which will roll further. Then do the experiment.
"The catfood will roll about twice as far as the soup, because energy is wasted as friction between the soup and its can.
"That experiment never goes wrong - except once, when the can was dented and it just went around in a circle."