The Problem
In parking metres, downtown,  you can get 15 minutes parking for 10c. Dad put a 20c and a 50c piece into the parking metre at 3.15pm. At what time did the parking metre expire?

What is this problem about?
This is a practical problem relating to both time and money. The children have to know the value of 50c + 20c as well as how many lots of 10c that is. Then they have to multiply the basic unit of 15 minutes by that amount. Finally that time period has to be added to the time.

Achievement Objectives
Measurement (Level 3)
- read and interpret everyday statements involving time
- show analogue time as digital and vice versa

Mathematical Processes
- devise and use problem solving strategies to explore situations mathematically (be systematic)

Resources
Blackline master of the problem (English)
Blackline master of the problem (Maaori)

Specific learning outcomes
The children will be able to:
- calculate using units of time and money
- communicate their reasoning clearly and using the correct units.

Teaching sequence

1. Introduce the problem with a short discussion about parking.
   How much does it cost? Has your car ever been towed away? Have you ever been given a parking ticket?
2. Give the children the problem to solve with a partner. As they work ask questions that focus on the strategies they are using to make the calculations.
   How did you work that out?
   How can you convince me that you are correct?
   Can you think of another way to solve the problem?
3. Ask the children to record their solution so that others could be convinced that they were correct.
4. Share the records. Dicuss whether the children have used digital or analogue time.

Extension to the problem
Get the children to write their own parking metre problem for others to solve.