Skip to main content
### Number and algebra

### Geometry and measure

### Probability and statistics

### Working mathematically

### For younger learners

### Advanced mathematics

# Magic Plant

## Magic Plant

On Friday at $9$ am, the magic plant was only $2$ centimetres tall.

Every twenty four hours, it doubled its height.

How tall was it on Monday at $9$ am?

### Why do this problem?

### Possible approach

### Key questions

### Possible extension

### Possible support

Or search by topic

Age 5 to 7

Challenge Level

- Problem
- Getting Started
- Student Solutions
- Teachers' Resources

On Friday at $9$ am, the magic plant was only $2$ centimetres tall.

Every twenty four hours, it doubled its height.

How tall was it on Monday at $9$ am?

This problem offers learners a context in which to practise doubling. It also gives children the opportunity to choose their own representation and recording methods.

You could start by asking children a different question, for example, imagining a magic plant that grows one centimetre every day. Explain that you are particularly looking out for what they choose to write down or do and offer them use of anything in the classroom that they feel would be helpful. Once they have had a go at this introductory task, share some of the different representations
they have made, making it clear that all of them have value and that each of us finds different things useful.

Then introduce the problem itself and again, leave children to work on it, perhaps in pairs. When you share their work this time, it will be interesting to see which children adopt a different form of representation than the one they used for the initial challenge. It might be worth finding out why some of them changed.

How tall will the plant be on Saturday at 9am?

How tall will the plant be on Sunday at 9am?

Some children might like to predict the plant's height at later stages during the week as well before working it out. They may well be surprised at how quickly it grows!

Some learners will find number line, number square or multiplication grid useful.