The other day my son was learning to work with negative integers. The concept of negative numbers is a little tricky to grasp for a kid.
So to explain the concept of a negative number, I took the example of temperature. The benefit of living in a place with 'real' four seasons helped. We started talking about rain and snow. I explained about when water freezes and how it is denoted as 0 degrees and how the temperature is measured when it goes below 0.
Started plotting some numbers on a number line. That kind of made him understand the concept of negative numbers. (On a different note, bloody Fahrenheit system in use here made my life a bit difficult during this time. I cannot understand why this country cannot adopt metric system.)
Once the concept of negative numbers was established addition and deletion of these numbers became easy. Just a question of pouring warm water over ice or dropping ice into warm water. Easy enough.
Then came multiplication and division. I gave him the easy solution. Just do the operation with the absolute values. Then just change the sign to negative, if either one of the numbers were negative in the first place. The answer remains positive, if neither is negative or if both are negative.
That solution worked but since the logic behind that was not understood, this became another formula that he had to remember. Explaining this was not as simple as dropping ice into water. In theory, it is the same but to explain it was not simple. So I changed tactics.
I went to his favorite subject - English. I took four words - Is, Isn't, Good, Bad.
I told him Is and Good are positive and Isn't and Bad are negative. Then I told him to write all possible combinations using these four words. He wrote
- Is Good
- Isn't Good
- Is Bad
- Isn't Bad
I asked him to choose which statements were positive and which statements were negative. He identified, rightly, Is Good and Isn't Bad to be the positive statements.
Now, it was easy for me to just point out that if there were two positives or two negatives the result is positive, whereas, if just one of the inputs is negative the result is always negative.
I was quite happy that I was able to make him understand Math by using Science and English! And it is funny to watch him murmur to himself this is good, this isnt good when he does his math work!