 On the bus: Recognizing addition and subtraction situations

# On the bus: Recognizing addition and subtraction situations

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## General

Students can recognize addition and subtraction problems using the context of a bus ride.

1.OA.A.1

## Relevance

Students can be supported in their understanding of addition and subtraction by learning to recognize addition and subtraction using the context of a bus ride.

## Introduction

Ask a few students to come to the front and create two unequal groups, one on the left, and one on the right. Ask students in the class to determine which group has more, and which group has less. Discuss the terms more and less and check that students are comfortable with their understanding of these terms.

## Development

Discuss the idea of recognizing math problems using the context of a bus ride. Tell students that using the context of a bus ride helps them to understand situations that involve addition and subtraction. Explain what it means when things are added, or taken away (subtracted) and that the signs + and - are used. Explain to students that the + tells us that passengers were added to the bus, and that there are now more passengers on the bus. Continue by explaining that the - tells us that passengers were subtracted from the bus (or exited the bus) and that there are now less passengers on the bus. Show students how to recognize addition in a bus problem. Show students that on the bus on the left, there are 2 passengers on the bus. The bus stops at the bus stop, and when it leaves, shown by the bus on the right, there are 4 passengers. 4 is more than 2 which means that there are more passengers than when they stopped, which means that passengers were added. Then show students how to recognize subtraction in a bus problem. Show students that on the bus on the left, there are 2 passengers on the bus. The bus stops at the bus stop, and when it leaves, shown by the bus on the right, there is only 1 passenger on the bus. 1 is less than 2, which means that there are less passengers than when they stopped, which means that passengers were subtracted (or exited the bus). Practice adding to and subtracting from on the next two pages. Each page shows three images, a bus on the left with passengers, an empty box in the middle, and a bus on the right with passengers. Look carefully at how many people are on the bus on the left and on the right and decide as a class if passengers were added to or subtracted from the bus. If passengers were added to the bus, drag a '+' sign to the empty box in the middle. If passengers were subtracted from the bus (exited) drag a -'' sign to the empty box in the middle. Then practice adding to and subtracting from by circling the correct bus on the right. On the left there are busses with passengers, in the middle there is a '+' or '-' to show if passengers were added or subtracted. Only one bus on the right can be correct and should be circled. Repeat this, but in the next exercise you can't count the passengers because they are represented by a number.

Check that students are able to recognize addition and subtraction situations using the context of a bus ride by asking the following questions:
- Where do you look to see if it is an addition or subtraction problem?
- If there are three passengers on the bus, and then after the bus stop, there are five passengers on the bus, is it addition or subtraction?
- Can you give an example of a bus problem with subtraction?

## Guided practice

Students are given problems in which they must decide if an addition or subtraction problem is being shown and selecting either the '+' sign or the '-' sign. They must then decide which image would complete the problem shown, with a bus with more or less passengers. Students are also asked to determine how many people would be on a bus which has had passengers added or subtracted.

## Closing

Repeat the learning goal and ask students what they should look at to determine if it is an addition or subtraction problem. Then discuss a problem out loud and ask students to determine if it is an addition or subtraction problem. For example: There are three people sitting on the bus, after the bus stop, there are five people on the bus- is this addition or subtraction? You can ask if any students can come up with an addition or subtraction problem using the context of a bus ride. To close the lesson, finish with a game. Set 10 chairs in a row and have a few students sit in the chairs. One student is asked to close their eyes. The teacher then points at students to either join the bus, or to exit the bus. The student whose eyes are closed must now open their eyes and decide if students have been added or subtracted.

## Teaching tips

Students who have difficulty with this learning goal can be supported by the use of manipulatives like MAB blocks, and to count to see if any blocks need to be added or taken away in unison with what is being shown in the images.

## Instruction materials

Optional: MAB blocks or other manipulatives. 