An external force acting
Teaching Guidance for 5-11 11-14
Wrong Track: When you drop a ball it just falls. It falls to the ground 'cause it's heavy.
Right Lines: When you release a ball from your hand it accelerates to the ground because of the gravitational force of the Earth pulling on it.
Objects fall because of the gravitational pull of the Earth
Thinking about the learning
A key step on the journey is to move away from thinking that objects fall because they are heavy. In other words, believing that it's something within the object (its heaviness) that makes it fall. The Newtonian view is that objects fall because of the action of the external gravitational pull of the Earth.
Thinking about the teaching
A possible activity is to set the pupils the challenge of
battling the pull of gravity. This involves taking the class to the school gymnasium and getting volunteers (there's never a shortage) to hang from a horizontal bar so that their feet are just clear of the ground. You can then time how long each can
withstand the pull of gravity.
The idea here is to set up a situation where the pupils can get the idea (and feel) that gravity is pulling them down towards the centre of the Earth. It is always a memorable lesson as you encourage the pupils to
battle against the pull of gravity and ask
can you feel the pull of the Earth?.
Interestingly, its often the little, thin pupils who can withstand the pull of gravity the longest, with the more likely
stronger boys struggling against the larger gravitational pull on their greater masses.