Ten Plus Bonds: Strategy -9
To develop the strategy of taking away 9, by taking away 10, then adding one, for wholes less than 20.
For example, to solve 15 – 9
Prior knowledge of ten plus bonds, adding and subtracting ten and one, and subtraction solved using take away on an empty number line is needed.
Please, click this link to read Teacher Notes for information about block placement when “Solving Subtraction Using Taking Away or Adding On”.
- take away
- left, right
A little easier
Before using the Bonds of 11 to 20: Near Ten Strategy -9 as a game for pairs, students can use this as an activity board to individually calculate each question in counting order. Work clockwise around the spinner, from the 12 o’clock position. Do not flick the spinner. Assist students to identify patterns.
A little harder
Near ten strategy -9
Play Bonds of 11 to 20: Near Ten Strategy -9 a little harder. In the game students have to subtract 9 from wholes in the twenties using the same strategy.
The blocks are a scaffold to support calculation. If students can calculate without some or all of the blocks encourage this. Below is a progression of reducing scaffolding, from most to least support, using near ten for 25 – 11.
This is the final activity in the Bond Blocks system of addition and subtraction to 20.
Retest students to using the Bond Blocks Addition and Subtraction to 20 Test to ascertain and celebrate progress. Then use this information to repeat activities that students have not yet developed fluency with.