MTS Math 7.5 Subtraction Charts

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MATH DEVELOPMENT ALBUM

7.5 SUBTRACTION CHARTS

CHART 1

This is a control chart. It has one set of facts for each combination for the numbers 1-18. The child uses this chart to check his problems or two children can use it to drill each other on the subtraction facts.

CHART 2

The finger chart. The numbers -9 through -1 are set diagonally along the left side of the board in blue; the numbers 18 down to 9 are in a red band across the top; the numbers 9 down to 0 are set diagonally along the right side of the board in red. This chart is used like the Addition Finger Chart: place the right index finger on the first number of the problem (top row) and the left index finger on the number being subtracted (left row); bring the right finger down and the left one over until they meet.

This Chart can be used to check answers or with the box of problems and answers.

CHART 3

The "Blind Chart". The child uses this chart only after he has learned all of the subtraction facts. Used like the "Addition Blind Chart", the child finds the first number on the top row with his right index finger and the second number on the row at the left with his left index finger; he brings the right finger down and the left finger over until they meet on an empty square; he selects and places on this square the number tile which gives the correct answer to the problem.

Child can make up his own problems or use the box of subtraction problems (as with Chart 2).

CONTROL OF ERROR:

The control chart

POINTS OF INTEREST:

1. Working with a friend to drill each other on the facts.

2. Using the control chart to check one's written work.

3. Using the problem box.

4. Filling in all the squares on the "Blind Chart".

AIMS:

1. To learn the subtraction facts.

2. To gradually transfer from concrete to abstract representation of subtraction.

3. To develop concentration and independence.

4. To develop a sense of accuracy.

VARIATIONS/EXTENSIONS:

1. Writing problems and answers.

2. A ditto sheet of problems to solve.

3. For older children, have them find an answer (chart 2) and write the problem.