Making tests fair

Sometimes you will have to do some tests before you can answer a question. A: Example

Imagine that some of your plants are dying. Your question is, ‘Why are some of my plants dying?’

Perhaps you have not been watering them enough.

Perhaps you have been watering them too much.

Perhaps they are not getting enough sun.

Perhaps they are getting too much sun.

To find out if you have not been watering them This is a test. If the plant recovers, you will have enough, you will have to give them more water. answered your question. Your plant was dying because you did not give it enough water.

B: Example

Here is a test that Tom did. He wanted to find out which kinds of beans sprout fastest. He put three different kinds of beans into containers, like this:

After a week, Tom noticed that the beans in jar (b) had sprouted first. He concluded that this kind of bean seed sprouted faster than the other kinds. But his test was not a fair test. Can you see why?

Tom’s test was not fair because the beans were not grown in the same way. For example:

The seeds in (a) were grown on wet blotting paper, but the others were grown in soil.

The seeds in (c) were under the soil, but the seeds in (b) were on the top.

The seeds in (a) and (b) were in glass jars so they got plenty of light. The seeds in (c) were in a tin.

Perhaps if the seeds in (b) had been grown under the soil, they would not have sprouted first.