Shoes weight and friction

Students use there own shoe, yes can get smelly, and use a newtonmeter to pull along a table, as the shoe is steadily moving the force being used is recorded. The experiment is repeated but with 100g mass (1N weight) is put into the shoe and so on with more weights
Studnts should spot the pattern of larger forces needed with heavier weights. This goes some way in explaining why big kids seem to have more grip