Arrival Craft: make ‘climbing critters’ (paper shapes with two bits of straw and one penny taped to the back, and a long piece of wool threaded through the straws, pull the wool to make the critter ‘climb’ the wool).
I found this craft here.
Demonstration: get the children to rub their hands together, explain that the heat they feel is caused by friction. Friction doesn’t just make your hands feel hot, it also slows things down when they’re moving. If you have enough friction it can stop things moving at all. Do the floating rice bottle trick (this is where you show two bottles of rice, you put a pencil in each one – traditionally, it’s a chopstick, but I found that the edges of a pencil gave a firmer hold – you lift one bottle up just by picking up the pencil, and invite your audience to try with the other bottle, but they find it to be impossible), ask the children if they know the difference between the two bottles. The rice bottle that I can lift with the pencil has much more tightly packed rice in it. Pour rice into bowls to show the different amounts. The tightly packed rice produced so much friction that it’s strong enough to hold the pencil in place and let me lift the bottle up.
Show an example techcard model, demonstrate how doing it up too tightly creates too much friction and stops it working.
I love techcard. I got a pretty good deal on it from Hands On. So, if you are interested in getting some, it’s probably worth shopping around. For this session we used something called Storybook Classpack. But the packs are very flexible!
Friction is not always a good thing. Often, engineers try to reduce the amount of friction, as we will be doing here.
Individual Task: make a model using a very simple lever, smaller children will need a lot of help.
Gather together: show off our models. What we have made is a simple lever, but levers can be used in different ways. Levers are a great way of lifting heavy loads. Make a ruler into a lever, and see how little weights can lift bigger weights if we move the little weights further from the fulcrum.
Break for drink and snack
Active Science: try and set up a line of dominoes, knock down the first one and watch the rest fall, to see how one push can have a lot of effects.
- Testing different car tracks to see how much friction slows a toy car.
- Littlies can play with toy cars on a mat with various different surfaces.