Activity 2 on number lines

Sum of numbers

Objectives

1. Using the number line model to find sum
   
2. Solving and creating puzzles using the number line
   
3. 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

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?
  
  

Worksheets

Activity Keywords

To link back to the concept page Numbers