Muscle making with balloons!

Make a model of the arm to show how the bones and muscles work.


A great practical to finish off the work on this topic. It helps that the children have covered all this topic to consolidate and embed their learning. It particularly relates well to the non-statutory guidance which states that children could be introduced to finding out “how different parts of the body have different functions.”

This activity also develops working in groups, communication and is a suitable investigation for mixed ability groups.

It also develops measuring skills in maths. Write the investigation up as a set of instructions for a cross curricular writing.

Year group:  3
Learning objective:

“Identify that humans and some other animals have skeletons and muscles for support, protection and movement.” (NC).


* 3 strong, good quality cardboard tubes-a set for each group.

*Tip-start collecting these before the investigation as the tubes need to be strong enough for the investigation. It is worth looking for the correct type*

* modelling balloons-4 each group. These need to be the long, straight ones to make the investigation work properly. Ordinary party balloons won’t work.

* a pump may be needed. These balloons are difficult to blow up, although can be done by an adult.

* scissors *rubber bands * paper clips* felt pen* skeleton if possible to help the children visualise the position of the ulna and radius and humerus in the arm.

* A ball of blu-tac or plasticine can be used to help make the holes in the tubes- this helps to stabilise making a hole in the tubes.

Working scientifically: (LKS2).
  • asking relevant questions and using different types of scientific enquiries to answer them.

  • Set up simple practical enquiries, comparative and fair tests.

  • Record findings using simple scientific language, drawings, labelled diagrams, keys, bar charts and tables.

  • Using results to draw simple conclusions, make predictions for new values, suggest improvements and raise further questions.

  • Identify differences, similarities or changes related to simple scientific ideas and processes.

  • Use straightforward scientific evidence to answer questions or to support their findings.

  • Make systematic and careful observations and, where appropriate, take accurate measurements using standard units…

Length of activity:

between 1 and 1 and a half hours.

Step by step:

1. Recap on roles and functions of bones and muscles- can be done verbally in mixed ability groups or as a class session. Record in science books or on post it notes to stick into floor books.

2. If you have a skeleton show the children the bones you are going to use in the practical, reminding the children about the relationship with the muscle.

3. Decide on a tube which is the longest and ask the children to label it as the humerus with the two remaining as the ulna and radius. Measuring the correct lengths can help embed maths work.

4. When all three are labelled, put the humerus in between the two other tubes. There should be about 5cm of the long tube in between the other two.

5. Draw dots for the holes you will make in the tubes. The holes for the smaller tubes should be at the top of the tube where the longer tube sits in between them.

6. The holes for the long tube should be at the bottom of this tube where it sits between the smaller ones. You should have marks for six holes altogether.

7. Line up all the holes. Make sure you take care when you make holes using a pencil with the ball of blu tac or plasticine behind it.

8. Take a paperclip and straighten it out. Thread it through all the holes in the tube and bend the ends back into the tube.

9. The humerus should move hinge like between the radius and ulna. Take a rubber band and wrap it round the bottom of the smaller bones. It may need to be double wrapped to ensure it is secure.

10. Take the balloon and blow it up until it is the length of the humerus. Leave enough of the balloon deflated so you have 2 equal lengths at each end so you can tie it around the humerus. Tie the other end around the ulna and the radius. Double tie for extra security if needed.

11. Take a second balloon and do the exact same but on the opposite side. Beware the balloons can pop at this point! You can then label the muscles as the bicep for the top one and tricep for the bottom.

12. Using a child as an example, get them to move their arm up and down. The children can use their model to show how the bicep bulges when the arm is moved.

13. Write the investigation up as a set of instructions.

Questions for children:
  • How do the bones and skeletons work together? Do they move at the same time?

  • ​Explain how the muscles relax and contract when an arm moves?

  • ​What is the specific function of the bicep, tricep, humerus, ulna and radius?

Expected outcomes:  
  • Children will identify and be able to explain the role and function of the tricep, bicep, humerus, ulna and radius when an arm moves.

  • Children will be able to describe the relationship between the bones and muscles when moving an arm up and down.

Possible misconceptions:
  • Muscles alone are responsible for movements.

  • There is one muscle in the arm.

  • That the muscles are in the same position and state during movement.

By Sue Evans, Science Coordinator at Phoenix Primary



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