Fun science: Pushes and pulls
14 September 2009Add to My Folder
Try these simple activities and basic investigations to help your class understand the nature of forces
Pogo sticks are perfect for investigating pushes and pulls!
Pushes and pulls are the two basic forces that children will most easily identify. Challenge children to label objects they push or pull, and encourage them to think about forces they use as they shape malleable materials. Physical games also give plenty of opportunities for investigating forces. Science educational resource provider, Philip Harris, teamed up with Holden Clough Community Primary School in Ashton-under-Lyne in Tameside to explore some forces. Below and right are three fun activities that were tried and tested by Holden Clough Year 1 and 2 teacher, Helen Woolfenden.
1. Action and reaction
Aim: To understand that when objects move, speed up, slow down or change direction, a force (push or pull) is acting.
Resources: Wheeled toys (skateboard, scooters, ride-on toys); a safe environment and appropriate protection.
Activity case study
Helen divided the class into two groups and invited the first group to ride on the toys. The other children were asked to observe and think carefully about how the toys worked. On the word ‘start’, the children with the toys were asked to push off with their foot and accelerate along the ground in a straight line. They were then asked to use their feet to bring the toy to a stop. Helen asked the second group what was involved in the change of speed. Helen summarised and clarified the children’s comments by saying that if the children wanted to move forwards, they had to push backwards on the ground. If they wanted to go faster, they had to put in some more force by pushing their foot down backwards again and again. To stop, the children had to push forwards on the ground with their foot. If they didn’t touch the ground, the toy would eventually slow down of its own accord, as the ground was pushing back against the forward force of the toy. The second group then rode the toys but instead of riding in a straight line, were asked to change direction. Helen explained that the same push and pull forces were at work here – for instance, you push or pull a scooter’s handlebars to make it turn.
‘The class enjoyed this experiment as it was hands on and made the children think about what they had to do to speed up, slow down and change direction.’
2. Pogo sticks
Aims: To understand that the Earth’s gravity acts on us all, pulling us towards the centre of the Earth; to learn that springs resist pushes and pulls and that they can store energy and release it again as a force in the opposite direction.
Resources: Plastic pogo sticks.
Activity case study
Four children were each asked to use the pogo stick for one minute and then to explain how they thought it allowed them to bounce. Afterwards, Helen explained that a pogo stick contains a spring that compresses when you jump on it and pushes back with a force that bounces you up. Then, gravity takes over and you come down again.
‘The class experienced the force and resistance of gravity in a very obvious (and fun!) way by demonstrating it themselves with the pogo sticks.’
3. Super magnets
Aim: To feel the force of neodymium magnets, the strongest permanent magnets known (they are not electromagnets).
Resources: Neodymium magnets (These are made so that different poles face each other, which brings the two magnets together sharply (with a slight risk of pinching). They have handles so that they can be pulled apart with considerable force.)
Activity case study
The class sat in a circle and two children were asked to stand in the centre. Helen separated the magnets and gave one handle to each of the two children, who then placed them together and pulled away from each other simultaneously. Care was taken as the children could have fallen if the magnets separated suddenly. This was repeated until everyone had had a go. (Note: Neodymium magnets are strong enough to give a nasty pinch if your fingers are between the magnet and an object to which it is attracted. Strong magnets are capable of damaging computer hard drives and wiping the stripes on bank cards.)
‘The super magnets are great and the children loved them! We discussed how some forces have a stronger pulling power, like these.
4. Mini ramps
Aims: to learn about exerting an unchanging force (gravity) on a moving object. To learn about identifying and controlling factors in a controlled investigation, taking measurements and that repeating an investigation gives more reliable results.
Resources: simple ramps; mini vehicles; measures; mini ramps and surfaces; graph paper.
Activity case study
The children worked in pairs to measure the distance the car travelled down the ramp. They altered the height of the ramp ten times and recorded the distance each time. They were asked to consider the following:
- What are you changing? (Height of ramp.)
- What are you observing or measuring? (Distance car travels.)
- If you change the height of the ramp, what will happen to the distance the car travels?
- What are you keeping the same to make the investigation fair? (Ramp, car, surface the car runs on.) The groups recorded their results in a bar chart – with the ramp height on the horizontal axis and the distance travelled on the vertical axis.
Afterwards, Helen asked:
- What difference did changing the height of the ramp make to the distance the car travelled?
- Why do you think that was?
- Do you think your results were accurate? Why?
- How could this have done better?
‘The children thought about the entire process of investigating and drawing results. It’s the perfect way to get them questioning what they are doing and what would happen if they change certain aspects of the experiment.’