## Friday, 2 April 2010

### Tips on Avoiding Mistakes (Unit writing)

.
Maths involves many traps.

Any one of this traps will make the solution looks odd or even to the extent of wrong answer.

What are this traps ?

Mathematical operators, symbols, units, transferring of numbers, size of the written symbols, decimal points are some of the examples of traps contributing to the error.

Here I would like to mention about "unit".

In maths, calculation of items are aplenty. One of them is the study of speed.

In the topic of speed, students are dealing with three basic elements.
They are the distance, time and their ratio (speed).

All these three elements have different units all to themselve.

Distance ==  metre
Time ==  second
Speed == metre / sec

There are variations of the above.
km, mintues, hours, km / h, m / min, etc

Do you now see the danger?

If you are dealing with so many units in one maths question, what are the chance of making mistakes?
If you are careful, the chance is low, but it does not mean zero.

You still have to be careful.

How to avoid having mistakes due to this undesired slip?

One tip is to write down the units in the working steps.
Do not leave the numerical answer (in the working) without any unit indicated.

Make clear the item of interest, whether it is distance or time by reflecting the unit besides the number.

Example:  5 km,  40 sec.

A complete maths example will push the message across, thus ....

Example :
Alan travelled at a speed of 60 km / h for 2 h. After that, he slowed down by 20 km / h and travelled the last quarter of the journey at this new speed. How long did he take to travel?

Working:
60  x20 = 120
120 / 3 = 40
60 - 20 = 40
40 / 40 = 1
2 + 1 = 3

What is your comment on the working?

I personally feel uncomfortable.  What about you?

The danger in that sort of working is the lack of showing the actual item in the calculation.
It does not allow a good way for checking after completing the worksheet (if many maths problems are within).

Clearly writing the units will, at least, make checking later an easier task.

It also allows the marker (teacher) a clearer picture instead of guessing what you intend to show.

Along the way, during the working, you will also have a lesser chance of getting confuse as the items are listed with the proper message (through the units).

So are you convince proper unit presentation is worth the while?