Purpose
The purpose is to develop useful strategies for mental calculation when counting in 10s and 100s.
Achievement Objectives
NA2-2: Know forward and backward counting sequences with whole numbers to at least 1000.
Specific Learning Outcomes
state the difference between numbers by counting in 10s and 100s
Required Resource Materials
A number line marked in 10s to 100, to 200 to 300 etc
A number line marked in 100s to 1000.
Activity
- Write 20 and 70 on the board. (vary the starting point to include numbers beyond 100 – as confidence grows then include numbers bridging the decades)
- Students take turns counting, verifying each others counting.
When you count from 20 – 70 how many times did you add 10?
What is the total of 5 tens?
How much more than 20 is 70? - Write 200 and 700 on the board. (Vary the starting point.)
- Students take turns counting, verifying each others counting.
When you count from 200 – 700 how many times did you add 100?
What is the total of 5 one hundreds?
How much more than 200 is 700? - Write 220 and 270 on the board. (Vary the starting point)
- Students take turns counting, verifying each others counting.
When you count from 220 – 720 how many times did you add 100?
What is the total of 5 one hundreds?
How much more than 220 is 720?
Add to plan
Level Two