You may also like

I'm Eight

Find a great variety of ways of asking questions which make 8.

Let's Investigate Triangles

Vincent and Tara are making triangles with the class construction set. They have a pile of strips of different lengths. How many different triangles can they make?


Noah saw 12 legs walk by into the Ark. How many creatures did he see?

The Amazing Splitting Plant

Age 5 to 7
Challenge Level

The Amazing Splitting Plant

The splitting plant grows in a special way.

In the first week, the stem splits into two branches.
In the second week, each of these two branches split into another two branches - making four branches altogether.

This keeps happening every week, until at the end of the sixth week each branch grows a flower.

How many flowers will the plant have?

Why do this problem?

This activity offers a situation that is not too complex to understand and yet opens out many possible explorations. It would be a good chance to focus on the different ways children have represented their solutions.

Possible approach

You could present the problem orally to the class, rather like telling a story. Ask them how many branches there would be by the end of the second week. You could then invite them to talk in pairs about the number of branches at the end of the third week.  Giving learners mini-whiteboards might help at this stage. How did they work out the answer? Having got this far, leave them to work on the problem in their pairs.

In the plenary, you could draw attention to the different ways of representing the problem you have seen. Some children may have drawn pictures of the plant, others may have just drawn lines. There may be some children who have simply noted down numbers. Invite several pairs to talk about their own representation and then you could have a group discussion about the advantages of each way.

You may want to make a note of the numbers of branches at the end of each week and to ask the children what they notice. Can they explain why this pattern occurs? Could they predict how many branches there would be after seven weeks (if there weren't any flowers) without drawing a picture?

Key questions

How many branches will there be after three weeks? Four weeks ...?
How will you keep track of the number of branches?
What kinds of things have you noticed?

Possible extension

Once children have solved the problem as it stands, the activity may be opened out and extended. For example:

1. If the plant branches in twos each year and we look at the units figure for a few years' growth we see year by year that the number of flowers [2 4 8 16 32 64 as in the problem] is:

2 4 8 6 2 4 ...

You can ask the pupils to see what they notice about the pattern.

2. Then you can pretend that the plant branches in different ways, maybe in 3s, 4s, 5s etc. For example the fours and fives units would look like:

The pupils can then be asked to explore what the patterns show and look at others for 6s 7s etc.
Further extension ideas are described on this sheet.

Possible support

You may want to talk to individual pupils about what is happening to the plant at each stage so they understand the context better.