1.
Grasp the ruler with your thumb and forefinger at the
end with the highest measurement and hold it at head level with
your arm extended away from your body.
2.
Ask one of your friends to be prepared to catch the
ruler with their fingers as you drop the ruler.
3. Have your friend position their thumb and pointer
(slightly open) at the bottom end of the ruler.
4. Release
the ruler and get ready to record their results.
5.
Write down the measurement where your friends thumb
grabbed the ruler.
6.
Try this with the rest of your friends and record their
results.
7. Now let one of your friends hold the ruler and
let you have a go.
Who had the quickest reaction? The person who catches the
ruler at the lowest end of the ruler has the fastest reflexes.
This sense of sight sends nerve signals to the brain when
it sees the ruler being dropped and then back out to the muscles
in the arm and hand to catch the ruler.