Parking meters
This problem solving activity has a measurement focus.
In parking meters downtown, you can get 15 minutes parking for 50c.
Dad put $3.50 into the parking meter at 3.15pm.
At what time did the parking meter expire?
- Calculate using units of time and money.
- Communicate mathematical reasoning clearly and using the correct units.
- Devise and use problem solving strategies to explore situations mathematically (be systematic).
This is a practical problem relating to analogue or digital time, and money. Students should have knowledge of how many minutes fit in an hour, should be able to operate on (e.g. add and multiply) increments of minutes, and should be able to make basic calculations using increments of 50c.
Problem
In parking meters downtown, you can get 15 minutes parking for 50c. Dad put $3.50 into the parking meter at 3.15pm. At what time did the parking meter expire?
Teaching sequence
- 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? - Give the students the problem to solve with a partner. As they work ask questions that focus on the strategies they are using to make the calculations. Provide the coins for students to use when making calculations involving money.
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? - Ask the students to record their solution so that others could be convinced that they were correct.
- Share the records. Discuss whether the students have used digital or analogue time.
Extension
Get the students to write their own parking meter problem for others to solve. The solution will be dependent on the nature of the problem.
Solution
$3.50 = 7 x 50c. 7 x 15 minutes = 105 minutes. 105 minutes = 1 hour and 45 minutes. 3:15 + 1:45 = 5:00. Dad can park in the car park up until 5 pm.