Using Difference Concept
Non-routine problems where the value is less than or more than that of another value involve the difference concept.
When applying this concept, you always minus the smaller value from the higher value. You can also apply algebra to
work on the problems which require difference concept.
Kids at lower primary school are not armed with the knowledge of algebra equations. Most of them have not reached the formal
operational level which is essential to learn the concept of algebra. As such the case, it is more suitable to use model approach.
Example. A plate of curry chicken rice and a plate of plasta cost $8. The plate of plasta cost two dollars more than the plate of urry chicken rice. Find the cost of the plate of plasta.
Yes, you can use algebra to resolve it easily.
x + y = 8 ---------- (1)
y - x = 2 ---------- (2)
For us adult, it is too simple to resolve but for primary school kid, it could be a challenge for them to grape the above concept.
So, one way is to use model approach. Draw bars to show the relationship between the cost of a plate of curry chicken rice and a plate of plasta. The bars can be
drawn as shown below:
| Plasta | x | $2 | } | $8 |
| Curry chicken rice | x |
Firstly, identify the highest value and that is the cost of the pasta (extra $2) and the lowest value is the curry chicken rice.
We substitube or denote the value for the lowest value as 1 unit. Take note, the higher value (Plasta) is x + 2. So the whole is $8 = 2x + 2.
To get the 2x, simple minus 2 from 8 (8 - 2 = 6)
2x = 6.
So if we want to get the x (which is the cost of the curry chicken rice), we use divide (6/2 = 3)
So the cost of the curry chicken rice is $3.
Now the cost of the pasta is simply $3 + $2 = $5.
To check, sum up both costs ($3 + $5 = $8)
To apply the model approach, you need to translate the problem statements into a model. The next step is to interprte the
model and form an equation that relates the value of the (higher values which is 6). Finally apply unitary or proportion concept to find the answer.
|
|
|
|
Follow Us To Get Latest Updates
|
|
|
 |
We would love to hear your feedback on how we can improve our site to serve you better.
|
|
|
|
|