Presentation
- Take a sum, e.g. 2170÷16.
- Get the quantity 2170 in stamps.
- The divisor is 16, so take a blue skittle, which stands for the share of 10.
- There are 6 units in the divisor, so we shall need 6 green skittles.
- Place them in a row.
- Before dividing out the stamps, clarify with the children that a green skittle gets 1 unit in stamps and a blue skittle gets 10 times as many; also, if a green skittle gets a 10, the blue skittle will get 10 times as many–100.
- Divide out the stamps amongst the skittles, starting with the highest category.
- When there isn’t enough of one category change for 10 of the next.
- The answer is 135, remainder 10–the share of 1 unit.
Other examples
a. With a category missing in the middle:
Setup and Materials
- Take a sum, e.g. 4224÷301.
- 3 red skittles
- 1 blue disc
- 1 green skittle.
Presentation
“What is our divisor 301 – so we need 3 red skittles. Are there any 10’s? No-so we use the blue disc to show the place of the 10’s. We also need 1 green skittle for the units. Now, if I give the green skittle 1 unit, what will I give the 10’s? Nothing, because there aren’t any 10’s, so how many will a red skittle get? 100. And if I give the green skittle 10, how many will the red skittle get? 100? No,if there was a blue skittle there that would get 100. 1000? Yes”
Start dividing out the stamps, changing where necessary, emphasising the difference in quantities given to the red skittle and green skittle. Change where necessary. The answer is 14, remainder 10-the share of one unit.
b. With the units as the missing category.
Setup and Materials
- Take a sum,e.g. 3456÷230
- 2 red skittles
- 3 blue skittles
- 1 green disc.
Presentation
Give a general explanation as before. Start dividing the stamps, changing where necessary. Be careful to stop when the blue skittles have received all the tens possible, because if the hundreds were given a ‘ten’, and the tens had a ‘unit’ what would the units have got if there had been any there? To find the answer, take the share of (10 children or) a blue skittle and further subdivide into 10. Lay out ten green skittles and divide out the stamps.
Answer:15, remainder 6.