What it shows
Adding is moving forward on a number line and subtracting is moving back. Hopping makes the idea physical and fun.
The science
A number line puts numbers in order, spaced evenly. To add 3 to 4, we start at 4 and move forward 3 steps to 7. To subtract, we move backward. Doing it with our body helps us see that numbers have a place and that addition and subtraction are opposite moves.
Materials
Cost: free. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- Chalk or masking tape (free)
- A flat floor or courtyard
- A small stone or beanbag
- Number cards 1 to 3 made from paper
- A friend
Safety
For this project: Play on a dry, flat, non-slippery floor. An adult must watch.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Draw a line of 20 boxes in chalk on the ground and write 0 to 20 in them.
Stand at 0 and throw the stone onto any number to pick a start.
Draw a number card from the pile to get a number to add.
Hop forward that many boxes and say the answer aloud, for example 5 plus 3 is 8.
Write the sum on a paper for score.
Next round, draw a card to subtract and hop backward.
Ask your friend to check by counting the boxes.
Play until one of you lands on 20 or 0.
What you should see
You can add and subtract small numbers by hopping and checking the answer by counting boxes.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1What does hopping forward mean?
Adding.
2What does hopping backward mean?
Subtracting.
3What is 7 plus 4?
Eleven.
4What is the number before 10?
Nine.
Take it further
Use a number line to 100 and hop in tens.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
Science projects
Easy Science Projects for Class 1 to 5
Simple, safe projects young children can make with a little help
Science projects
Maths Working Models and Activities
Make maths visible: models for number, geometry, algebra and data