# Activity 2 on number lines

## Sum of numbers

### Objectives

- Using the number line model to find sum
- Solving and creating puzzles using the number line
- Investigating the order property of addition

### Materials

Counters for the number line (chips, markers, etc.)

### Estimated Time

2 periods

### Materials/ Resources needed

Paper, Pencil, chalk, large room

### Prerequisites/Instructions, if any

### Multimedia resources

### Website interactives/ links/ simulations/ Geogebra Applets

### Process (How to do the activity)

Tell the students that they will find sums using the number line model. Then display a large number line and a 5+4 pencils , that is, a pencil with 5 spots on the left side and 4 spots on the right. Then demonstrate with a counter how a hop of 5 is taken on the number line. You may wish to encourage students to count aloud as the hop is made. Then make a hop of 4, starting at the place the counter landed. You might choose to have them record what happened using the equation notation 5 + 4 = 9, or to informally describe the moves this way: “If you take a hop of 5 spaces and then a hop of 4 spaces, you land on 9.” You may wish to highlight the fact that in this model, spaces are counted, not points on the number line.

#### Developmental Questions (What discussion questions)

- Which number did you land on when you made a 5-hop, then a 3-hop? Could you land on the same number if you took a 3-hop first, then a 5-hop? How do you know?

The answers could be yes [ 5 + 3 = 8, and 3 + 5 = 8.]. Laws of computation can be introduced.

- What sums did you model with hops? How did you record them? [Student responses will depend upon the "hops" they performed.]
- Were any of the sums the same? Why? [Student responses will depend upon the "hops" they performed.]
- How would you find the sum of 2 and 5? [Make a hop of 2, and then a hop of 5, to reach 7.]
- How would you tell a friend to add on the number line?
- How is using a number line like measuring? How is it different?
- Which students counted as they took hops and which moved directly to the number?

**Questions for teacher reflection**

- Which students had trouble using the number line? What instructional experiences do they need next?
- Did any children notice a connection with measurement?
- What adjustments would we make the next time that we teach this lesson?

### Evaluation (Questions for assessment of the child)

### Worksheets

#### Activity Keywords

**To link back to the concept page**
Numbers