# Measurement (length): Magical Narwhals

## The Problem

A narwhal needs to reach a new fishing ground. Unfortunately, there is a large obstacle in the way – sea ice! Luckily, there are cracks (leads) in the ice that the narwhal can travel along. However, the ice is moving and the cracks are starting to close up. The narwhal must get through the ice as quickly as possible.

Look closely at the map opposite. It shows the ice and the leads (coloured blue) that the narwhal can travel along. (You will be given a copy of this map.)

What is the shortest route that the narwhal could take to find its way through the ice? How do you know it’s the shortest route?

Did you know?

A narwhal’s tusk is actually an overgrown tooth! Some narwhals have one or even two tusks, while others have none.

## Visualising the Problem and Getting Started

• How many rectangles can you see within the ice sheet map? Which other shapes can you see within the ice sheet map?
• If a Narwhal travelled a distance of 20 cm on the map, how far would it have travelled in the sea?