Why do this problem?
offers an environment in which learners can "play" with symmetry. If possible, all pupils should be given a chance to investigate for themselves what happens to the green spot as the yellow one is moved. This might mean that it would be useful to be in a computer suite when trying this problem.
This activity might be best presented with very little introduction from you as the teacher and children simply left to explore in pairs. This will give you the opportunity to listen to the conversations taking place. Listening in this way will help you to gauge how sophisticated the language of the pupils is in relation to describing position and movement, and so you can introduce formal
vocabulary related to symmetry as they require it.
The second part of the question is much more challenging and might be worked on over several lessons.
What happens to the green spot when you move the yellow spot to the right?
What happens to the green spot when you move the yellow spot to the left?
And when you move the yellow spot downwards what happens to the green spot?
And when you move the yellow spot upwards what happens to the green spot?
The second part of the problem is likely to be sufficiently challenging. However, you could encourage children to create more than one tube.