First Chart
Materials
- A box containing slips, each slip has just one subtraction problem on it in the form of X-Y= . The box will contain all the possible subtraction problems the answers of which can be found on the chart.
Presentation
- As before, the child takes a slip, e.g. 4 -1 = .
- On the chart, the numbers in red stand for the quantity to be subtracted from.
- Ask him what that means. He must be able to explain and to understand it. The numbers in blue represent the number being subtracted. One moves one figures from the “red” minuend down, and from the blue subtrahend right. Where the two meet is the difference (or the “answer”).
Second Chart: Blind Chart
Materials
- A box of numbered tablets. These are square tables the size of the squares in the chart. On each tablet is printed a number that then will be the answer in the chart.
- A box of slips ( = essential problems) containing problems that cover each possibility in the chart.
Presentation
- Lay out all the tablets face upwards.
- As before, take a slip11-7= . ‘What is that?’ 4.
- Find the tablet of 4, and place it in its correct square.
YouTube example: https://youtu.be/f7YYlnL29gE
Control of Error
In the first chart.
Direct Aim
Memorisation of essential tables.
Age of Great Interest
About 6 years.
Control of Error Chart N.B.Please note the answers should appear in red.
involving the three aspects of subtraction. It is essential that he should have a knowledge of decomposition before he comes to do division.