Division
Sharing
Teenagers will benefit from sharing out items equally,
or breaking up 'whole' numbers into 'equal' parts. Fractions can be introduced by
sharing cakes, oranges, etc. and with worksheets (see Figure
42). 'Sharing' is the practical application of division, and can be reinforced
in the classroom, kitchen, meal table and many other social situations. The vocabulary
for division should be emphasised and repeated in discussion with teenagers with
Down syndrome, for example, 'whole', 'parts', 'group', 'share', 'split', 'separate',
'divide' and 'division'.
The
formal strategies for division are similar to those used in multiplication.
For the problem 15 ÷ 5, teenagers may use:
- Knowledge of multiplication: 3 x 5 = 15
- Knowledge of addition: 5 + 5 + 5 = 15
- Derived facts: 2 x 5 = 10, + 5 = 15
- Fact retrieval: 15 ÷ 5 = 3
When the language and symbols for division have been learned,
a framework can be used to practice division, similar to the example shown for multiplication.
Cuisenaire and other apparatus can be used to show division visually, to illustrate
problems, e.g. 10 ÷ 2, 20 ÷ 4.
Division has extra difficulties with language compared
to multiplication: the answer for multiplication is the same whichever way the numbers
are placed, but this is not so for division. Language such as 'divide X by Y', 'divide
X into Y', 'X is divided by Y' is hard for people with language and short-term verbal
memory difficulties to follow.
Odd and even numbers
Teenagers will understand the significance of odd and
even numbers when they learn to share and divide. Odd and even numbers to 10 or
20 can be learned by memory through games with numeral cards, with words on the
reverse reading 'odd' or 'even'. This knowledge will help them to understand 'odd'
and 'even' through other games and activities. Earlier work with Numicon shapes
will have helped to develop an understanding of 'odd' and 'even' numbers, as this
feature of number can be seen, felt and experienced through addition and subtraction,
multiplication and division games.