Material
- A board divided into 18 squares across from left to right and eleven squares from top to bottom. The topmost squares are numbered 1-18 (from 1 to 10 in red, and 11-18 in blue). There is a red line vertically dividing the board after the 10th square.
- Two sets of strips, one set in blue with symbols from 1 to 9, the other in red, subdivided into squares by blue lines. The end square of each strip is marked with the symbol which corresponds to the numbers of its squares.
- Prepared slips on which the children will write their answers. Each slip should contain a single addend addition table. Hence the first table would be with the addend being 1, and the summand being 1 – 9. Leave enough space after the equal sign for the child to write the answer.
| Addition with 1 |
|---|
| 1 + 1 = |
| 1 + 2 = |
| 1 + 3 = |
| 1 + 4 = |
| 1 + 5 = |
| 1 + 6 = |
| 1 + 7 = |
| 1 + 8 = |
| 1 + 9 = |
etc., etc., etc.
Direct Aim
To lead the pupil through all the possible combinations in addition. Showing that none exist beyond the combination of 9 + 9. The red line vertically dividing the board shows when the addition reaches beyond 10. (It has the same purpose as the notched cards in the snake game).
The essence of addition is the making of tens.
Presentation 1: General Introduction
- First show the child the strips and how they fit the squares.
- Lay out the strips, the blues on the left and the reds on the right.
- Take any numbers at random, e.g. the blue 6 and the red 4, and place them in the first row of the stripboard.
- Count from the blue strip 6, 7, 8, 9, 10. So 6 and 4 make 10.
- Take blue 8 and red 7. 8, 9, 10, 11, 12, 13, 14, 15. So 8 and 7 make 15.
- Say the number combinations clearly.
Exercise 1
Materials
- The board
- Strips
- Prepared slips.
- The teacher fills in the first one. ‘What is 1 plus 1?’ She finds the answer with the stripboard….2: So one and one make two, and she fills in ‘2’ on the prepared slip.
- The table of one is completed and the child then does the table of 2; filling in the slip on the reverse side.
- He completes all tables up to 9+9=18.
Control of Error: The child uses the Summary of Addition Table from lesson 21copied here.
Exercise 2: This leads up to the memorisation of the essential combinations.
- Show him how to find out the various ways of making up a number, e.g. 9.
- Place the blue strip of 9 on the board.
- Underneath place the blue strip of ‘1’.
- ‘What do we need to make up 9?
- Let’s try ‘8.
- Place the red strip of 8 beside the blue strip of 1, and count 1/2, 3, 4, 5, 6, 7, 8, 9, so 1+8=9′.
- He writes this in his sum book.
- Then he takes the blue strip of ‘2’, after replacing the other strips, plus the red strip of 7 and count 2/3, 4, 5, 6, 7, 8, 9, so 2+7=9, and so on, for all the combinations.
- The child experiments with any number he likes under 18.
- Let him discover for himself that 6+7=13, 7+6= 13; or 5+4=9, 4+5=9.
Control of Error: In the boards and strips.
Exercise 3: Concentration on the isolation of the essential combinations.
- Repeat all the tables, using the strips and the prepared slips.
- The table of ‘1’ remains the same.
- When he starts the table of ‘2’, he starts from 2+2=4. This is continued in the same way up to the table of 9, where there is only one necessary combination, i.e. 9+9=18.
Control of Error: “Summary Chart II” from lesson 21 on the Addition Tables copied here.