Multiplication by 10, 100, 1000
- Decimal system materials
- Black and red pencils
This activity is a prerequisite for the small bead frame
- The directress isolates a 10-bar.
- Directress asks the child; "How many units are there in 10?" 10.
- The directress isolates a hundred square and asks the child; "How many tens are there in 100?" "How many units?"
- Isolate the cube. Ask: "How many hundreds are there in 1000? How many units? tens?"
- "We can say that 10 tens is the same as 100, 100 tens is the same as 1000 and so on. "
- With the child draw relative conclusions of all the changes possible.
Directress write down a multiplication problem and ask the child to lay out the problem, using the golden bead material i.e. ( 21 x 10 =).
- The child, knowing the function of multiplication, combines these quantities and makes the necessary changes.
- With the answer - two hundreds, one ten, and the zero is written in red. 21x10 = 210 .
- Observe that the product is simply 21 (the multiplicand) with a zero after it.
- Do many examples of this type, including: 30 x 10 = 300
By one hundred
- Directress write down a multiplication problem such as 23 x 100 = and asks the child to lay out the material.
- We can't put out 23 one hundred times, we would run out of beads!
- We can multiply each unit by 100. Isolate one bead from the 23.
- 1 x 100 = 100 Substitute the bead for a hundred square.
- Repeat for the other two units. Then 10 x 100 = 1000.
- Replace each ten bar with a thousand cube, and so on.
- Record the product. 23 x 100 = 2300.
- Notice that the product has the same number of zeros as the multiplier.
By one thousand
- Directress write the problem 4 x 1000 =.
- As before, multiply each unit by 1000, replacing each bead with a thousand cube.
- Record the product 4 x 1000 = 4000. In this case we jumped from the units, past the tens, past the hundreds, to the thousands.
- For each hierarchy that we increased, one zero was added.
- Observe as before that the number of zeros in the product is the same as the number of zeros in the multiplier.
- The product is simply the number of zeros in the multiplier.
Control Of Error
Points Of Interest
- to be sure that the child has understood the concept of change
- To ease of multiplying by powers of ten, and understanding of the characteristic patterns of such multiplication.
- To prepare the child for multiplication using the bead frames.