T. Hesterrev. 2014
MECR/2014
Subtraction Strip Board
Materials:
Wooden board with a red grid of 2cm. squares, 17 across and 12 down.
The top row of squares is labeled from 1-9 in blue and from 10-18 in red, separated by a vertical blue dividing line. (This indicates that the remainder cannot be more than 9 with this material.)
Box of 9 blue and 9 red 2cm. wide wooden strips numbered from 1-9 according to length.
The red strips are marked with blue vertical lines every 2 cm.
Box of 17 unmarked natural woodenstrips representing lengths 1-18 on the same scale. Full Subtraction Control Chart. Table or rug large enough to accommodate the materials.
Preparation:
Addition Strip Board.
Age: 5-6 years.
Direct Aims:
To develop an understanding of the logical and orderly progression of the subtraction tables.
To memorize the subtraction facts.
Indirect Aims:
To develop order,concentration, coordination, and independence.
Presentation I – Introduction
Presentation II – Subtraction Table Booklets
Vocabulary:
Subtraction Strip Board, natural wooden strips, minus.
Points of Interest:
Appearance of the answer to the left of the strip.
The natural wooden strips.
The visual layout of the materials.
The orderly progression of the answers.
Choosing the correct natural wooden strip to do the problem.
Control of Error:
The board and the strips.
The correct placement of the strips on the board.
The Subtraction Control Chart I.
Variations:
- Put the red strip at the end of the blue strip when doing your problems as the answer.
Extensions:
Circle and chart paper.
Prepared Problem Tickets
- Invite the child to set up the Subtraction Strip Board.
- Show the child the box of prepared problem tickets.
- Choose a problem ticket out of the box. e.g. 14-6=. Write the problem down on the prepared paper (5 squares across and 9-10 squares down).
- Cover the numbers past 14 with a wooden strip. (Child has to, by trial and error, discover the correct wooden strip.)
- Place the 6 blue strip on the board covering the numerals 14-9 which will reveal the answer as 8.
- Write the answer on the prepared paper.
- Place the problem ticket in the smaller section of the problem ticket box.
- Continue in this manner, choosing problems, until the prepared paper is complete. Check answers with Full Subtraction Control Chart.
- Show the child how to put the materials away properly.
Subtraction with beads.(Can be used as an introduction to the Subtraction Strip Board)
18 green unit beads, 3 glass cups or containers, -sign, and an = sign. Choose the amount of units you want and put them in the first cup. Decide how many you want to take away. Place them after the –sign in the next cup. Count how many are left and place them in the third cup after the = sign.
Notes: