Composition and De-Composition

Material

  • Set of small number rods
  • a table mat.

Presentation: Addition (4½ years plus)

  1. The teacher works with the child on the table.
  2. Take the ‘10’ rod and place the’9′ rod underneath it.
  3. Ask the child to find another rod which would when added to the ‘9’ rod be equal in length to the ’10’ rod.
  4. Count the two rods together. ‘9 plus 1 equals 10’.
  5. Remove the ‘9’ rod and replace it with the ‘8’ rod and ask the child to find a rod which would again when added to ‘8’ make ’10’.
  6. Continue in this way exploring the composition of different numbers.

Direct aim

To show the working of addition.

Control of error

Visual. The child can see that the length of two different rods equal one longer one.

Presentation: Subtraction (41/2 years plus)

  1. The work on the table.
  2. Place the ‘6’ and ‘4’ rods in a line.
  3. The child counts the sum i.e. ’10’. Take one of the rods and the child counts it, he also counts the remaining rod.
  4. “We had ’10’, we took away ‘4’ and were left with ‘6’”.
  5. Repeat the exercise using different combinations to give the child more practise.

Direct aim

To show the working of subtraction (De-composition).