This problem offers you two ways to test reactions - use them to investigate your ideas about speeds of reaction.
Imagine a machine with four coloured lights which respond to different rules. Can you find the smallest possible number which will make all four colours light up?
Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?
Here is a machine with four coloured lights. Can you make two lights switch on at once? Three lights? All four lights?
To investigate the relationship between the distance the ruler drops and the time taken, we need to do some mathematical modelling...
Can you suggest a curve to fit some experimental data? Can you work out where the data might have come from?