Testing our reflexes
When we decide to move our hand, our brain sends out signals to the muscles in our hand, these shorten, and the hand closes. The same thing happens with all our muscles and joints. But there is also another type of movement, one which we don’t think about, like balancing to keep upright. These movements are called reflex actions, when a muscle automatically moves without the brain needing to think about it.
You will need:
- Two volunteers
- Two high stools
- Two wooden strips about 30 centimetres in length (or rulers).
- Adhesive tape
- Two large erasers – preferably with a slanting edge.
- A very long ruler or a small plank
- Two pieces of polystyrene of equal weight
- And something in the form of a prism/triangle to make a see-saw.
And last but not least ... a helping hand from an adult.
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Method
The aim of this experiment is to discover which volunteer has the faster reflexes.
First you need to make two small hammers. Start with one of the two 30 centimetre wooden strips/rulers, an eraser, and some adhesive tape or rubber bands. If the eraser doesn’t have a slanting edge, ask an adult to cut a slanting side. Put the eraser on the table lengthwise, and place the wooden strip over it so it looks roughly like a hammer. Now fix the eraser well to the wood using adhesive tape or rubber bands. Do the same to make the other hammer.
Now you need to build a small see-saw. Place the triangular object on the floor and balance the plank on it. You need to place two equal blocks of polystyrene on each end of the see-saw, so that the plank is balanced. Then gently place the stools behind the see-saw, so that when the volunteers sit on them, their feet will be level to the polystyrene blocks.
Now you have to use the hammers to lightly hit your volunteers below the knee cap. If you hit correctly the leg will automatically jerk upwards and forwards. You should practice you are comfortable at doing this well.
The volunteer who kicks the polystyrene block first, has the fastest reflexes. The see-saw will tilt up at the side where the polystyrene was kicked of first.