We use are eyes to see when the pencil is released.
As soon as we see it move we grab to catch it.
Our brain receives the information from our eyes, decides what to do and tells our fingers to close.
This process takes a short length of time.
We call it our ‘reaction time’.
Different people have different reaction times.
A stopwatch can measure time accurately yet it isn’t very useful in this experiment. why?
The falling pencil works quite well but we have to compare how much of the pencil has passed your fingers before you catch in order to compare your ‘time’ with someone else.
The pencil doesn’t have any marks to allow a measurement to be made.
A ruler works better because we can see on the scale how many cm of ruler has passed before we catch it.
A ruler lets us measure reaction time not in seconds but in ‘cm of ruler’!
Once we can measure and record we can study the results, make comparisons and decide what to do next – this is what ‘investigating’ is all about.