Two students, Mia and Noah, carry out an experiment to determine the average speed of a runner on a school sports field.
Mia measures out the distance of the run by placing her feet heel-to-toe.
She records:
'Distance = 50 shoe-lengths'
Noah uses his pulse to estimate the time taken for the runner to complete the distance.
He records:
'Time = 12 heartbeats'
Give three ways the students could improve their experimental procedure to obtain a more accurate value for the speed.