Skip to main content
### Number and algebra

### Geometry and measure

### Probability and statistics

### Working mathematically

### Advanced mathematics

### For younger learners

# Sea Level

## You may also like

### Pebbles

### Bracelets

### Sweets in a Box

Or search by topic

Age 7 to 11

Challenge Level

What can you see in this picture? You can click on it to make it bigger if you would like a closer look.

There are black markings all the way up the lighthouse right to the very top, and on the rock that the lighthouse is built on, going down to the sea bed. These markings are 1 metre apart.

We will call sea level '0' and then we could think of the lines as representing positive numbers going upwards and negative numbers going down to the sea bed.

In this task, we are going to look at where the mouths of each of the different animals are. This will allow us to see how deep they are compared to each other, or what distance apart they are.

For example, the seahorse's mouth is 1 metre deeper than the mouth of the blue and yellow fish.

Have a think about these questions, or you might like to make up some of your own:

- What number should be where the head of the seagull is?
- What number should be where the mouth of the crab is?
- How far up is it from the head of the shrimp to the mouth of the shark?
- How far from the surface is the eel's mouth?
- How high above the sea level is the seagull's beak?
- How much higher is the seagull's beak than the seahorse's mouth?

How did you arrive at your answers? Did you write anything down to help you?

Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?

Investigate the different shaped bracelets you could make from 18 different spherical beads. How do they compare if you use 24 beads?

How many different shaped boxes can you design for 36 sweets in one layer? Can you arrange the sweets so that no sweets of the same colour are next to each other in any direction?