Discuss that it is important to be able to calculate subtraction problems to 10 using the bus ride as context. Using the three images, explain how bus problems work. The first image shows how many passengers are on the bus as it arrives. The second shows how many passengers exit the bus at the stop. The third image shows how many passengers are left on the bus as it leaves. You can determine this third image total by taking away the number of exiting passengers from the total number of passengers from the first image. Show the students the subtraction problem that matches the images, namely 2 - 1 = 1. Ask students to name which number is the first number of the subtraction problem (minuend) which is the second number of the subtraction problem (subtrahend) and what is the total, or difference. Tell students that they can check their work by adding their total (difference) and second number (subtrahend) together.
Next practice two more bus examples on the interactive whiteboard. Explain to students that the images will now stay the same- you can have all the information in just one image. Practice this with two bus examples and show students that they can also solve using the bus method even when they can't count the individual passengers, but are given numbers to represent the number of passengers on the bus. Practice with the students.
To check that students are able to subtract numbers to 10 using the bus method, you can ask the following questions:
- Which steps do you take in solving subtraction on the bus?
- How many passengers are still on the bus if there are 3 passengers and 2 exit the bus?
- How many passengers are still on the bus if there are 8 passengers and 5 exit the bus?