Make your own solar system provides ideas for a STEM club for up to half a term.

This project links science and maths in an integrated way, and can be approached at a level appropriate to the students so that there is sufficient challenge for the more able, while providing an accessible project for others.

This obvious focus of this project is astronomy but it also covers maths and science, and has the potential to be related to geography also. This should help students to integrate what they learn in lessons as they investigate the topic.

This project starts with creating a model of the solar system using an unrolled toilet roll for the distance between the Sun and Neptune. The initial task is to decide how this can be used to scale the distances involved. Once we add in the sizes of the planets, things get more complicated! How do we resolve the problem of representing different orders of magnitude in the same model?

When the model is complete, students can make posters describing the planets, and their potential for space exploration.

The model and posters or other artefacts would make an excellent display for a parents' night or other public event.

This whole project is intended to be group activity. Depending on how many people there are in your club, you could divide students into smaller groups, or all work together. One possibility is to start off as a whole group, then let students work in smaller groups on particular questions they want to investigate further.

There are information sheets to help students get started:

- getting started - scaling the distances in the solar system
- scaling the planets and improving your model

While students are enjoying creating their model, they will have to make decisions about scale. A way into this is to start with relative distances and sizes - getting things in the right order - then introduce numbers.

You could start by unrolling the toilet roll in a large space and putting the largest ball available at one end for the Sun, and a fairly large ball at the other end for Neptune. Then ask the students to choose objects for the other planets, and to put them where they think they might go. This requires them to find out about relative sizes and their order out from the Sun. They should take some notice of the actual distances, rather than just putting them at regular intervals.

Then comes a key question: is this good enough, and if not, how do we make it more accurate?

This could lead into a brain-storming session, where students suggest how they might use the toilet roll to scale the distances. Once objects are placed on the toilet roll in the right places, it would be good to discuss how accurate the guesses were - are there any big surprises?

The next stage is to replace balls and small spherical objects with models or objects which are scaled correctly. Is it possible to use the same scale as the distance scale on the toilet roll? If not, why not?

How is this to be resolved? Are you going to use a different scale for distances and for planetary diameters? Or are you going to buy more toilet rolls to make a longer model? Or ... ?

- What information do we need to get started?
- Is our initial model good enough? How can we improve it?
- Do we start with the toilet roll, or with the distances from the Sun to the planets? Are we going to make our scale unit one sheet of toilet paper or some other number of sheets of toilet paper, or are we going to make our scale unit 10,000 km or some other number of km?
- If our scale unit is a number of sheets of toilet paper, how many km does the unit number of sheets of paper represent?
- If our scale unit is a number of km, how many sheets of toilet paper are we going to say are equivalent to the unit number of km?
- Once we have determined the scale, and put the planets in the right places on the toilet roll, what can we say about the solar system? What are our observations?
- Thinking about the sizes of the planets - what do we mean by 'size'?
- Given the unit we decided on for the distance model, can we represent the planets using the same unit?
- If not, how are we going to resolve the problem so we can finish our model?

DIY data table is the worksheet students could use to help them work out distances and sizes on their model.

More data gives the numbers of moons and the lengths of days and years for each planet.