MTS Math 7.1 Subtraction With The Red And Blue Rods And/Or Table Top

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MATH DEVELOPMENT ALBUM

7.1 SUBTRACTION WITH THE RED AND BLUE RODS AND/OR TABLE TOP NUMERICAL RODS

MATERIALS:

Red and Blue Rods or the Table-top Rods. Minus and Equal signs (the size should correspond to the width of the rods used).

Later: Numerals (size to match the rods)

PREPARATION:

This should be presented to the child who has worked with the decimal system and addition using the rods. Other subtraction work could have been done prior to using the rods also. Large red and blue rods should be used on the rug, small rods on a table top.

PRESENTATION:

1. Build the stair using the rods. Place the longest rod at the top with the one rod closest to the child.

2. Review how the number rods when combined make different numbers (refreshing their concept of addition)

3. Explain to the child that addition puts things together and subtraction takes them apart again.

4. Place the 10 rod in front of the child. Select 2 rods which equal 10 (i.e. 6 and 4) and place them under the 10 rod. Say, "If we take the 4 rod away how many do we

5. have left".

6. Point to the 6 rod and say, "There are 6 left. We can now say that 10 take away 4 equals 6"

7. Take the numerical symbols and place them under the rods.

8. Take the minus sign and place it between the 10 rod and the 4 rod. Place the equal sign after the 4 rod and place the 6 rod after the equal sign.

9. Now bring the minus and equal signs down between the numerical symbols and show the child how it looks using numerical symbols.

10. Repeat this process for other equations using the 10 rod as your minuend.

11. Ask the child to read the problems with you as they are completed.

CONTROL OF ERROR:

1. Seeing the incorrect alignment of the rods.

2. The child's knowledge of quantity and symbols

3. Counting the places on the rods

4. Another child

5. The directress

POINTS OF INTEREST:

1. Noting the similarity of the table top rods and the long red and blue rods. Color and quantity the same.

2. Seeing the minuend and then taking away the subtrahend.

3. Seeing the remainder

4. Seeing subtraction problems being created

5. Seeing the minus sign

6. Using the equal sign

PURPOSE:

Direct Aims:

1. Showing the child how subtraction is the interest of addition

2. Enticing the child to do additional work with the rods giving a concrete approach to subtraction

3. Preparation for further operations with the golden bead material

Indirect Aims:

1. Prepare the child for higher levels of subtraction

2. Further development of the math mind

AGE:

3.5 and up

VARIATIONS:

1. Can make teen numbers and have the child create problems

2. Allow the child to create their own problem

3. Have the child use problem slips (pre-made equations)

4. Have the child use structured cards with tables on them

NOTES: