Problem
Sally the Snail crawls 2cm each minute. Sally needs to rest at each dot for 5 minutes. How many minutes will it take for her to get from the path to the plant?

(see blackline master for picture of the path)

What is this problem about?
This is the use of arithmetic in a practical situation using time and distance.
As the calculations involved in this problem involve single digit addition and multiplication it offers a good opportunity to encourage the children's use of mental strategies. Research has shown that an emphasis on oral and mental calculation forms the basis for a strong grasp of number.

Achievement Objectives
Measurement (Level 2)
- carry out practical measuring tasks, using appropriate metric units for length, mass and capacity

Mathematical Processes
- devise and use problem solving strategies to explore situations mathematically

Resources
cm rulers
picture of a snail (for introduction)
Blackline master of the problem (English)
Blackline master of the problem (Maaori)

Specific learning outcomes
The children will be able to:
- Measure using cm.
- Solve problems using minutes as the unit.

Teaching sequence

1. Get the children to estimate 2 cm using their fingers. Ask:
   What do you use to estimate 2 cm?
2. Introduce Sally the snail and the time it takes for her to travel 2 cm. Ask:
   Do you think that 2 cm is reasonable?
3. Pose the problem for the children to work on with a partner.
4. As the children work ask questions that focus them on communicating the steps they took to solve the problem.
   What was the first thing you did when solving the problem?
   Could you solve it another way?
   How do you know that you are correct?
5. Share solutions.

Extension to the problem
Get the children to create their own snail problem for others to solve. The may decide to vary the speed that Sally moves.