Experiment

A. Study the scenario described below. It illustrates what an experiment is.

Ms. Gatdula was invited by a friend to visit her in Baguio City. Before leaving her home in Manila, she instructed her helper to feed the fish in the aquarium during her absence.

It was May. The summer heat was almost unbearable. The helper was worried about the fish entrusted to her.

One very warm afternoon, she got a tray of ice cubes and put all of them into the aquarium. In just a short while, all the fish in the aquarium died.

Anthony, a nephew of Ms. Gatdula, learned about the tragic incident. But he did not reprimand the helper right away. He wanted to be sure of the cause of death of the fish. Here is what he did:

·         He bought six fish of the same kind as those that had died. He kept them in the aquarium for two days.

·         Then he got two large wide-mouthed bottles, or glass jars, of the same size. He labeled one Jar No. 1 and the other Jar No. 2 He put the same amount of water and three fish in each jar, together with some aquarium plants.

·         When the fish had stayed in the jars for two days, he put ice cubes in Jar No.1

·         He observed that the fish in Jar No. 1 died. Those in Jar No. 2 did not.

Now answer the following questions.

1. For his investigation, why did Anthony buy the same kind of fish as those that had died? Could he not have used just any kind of aquarium fish?

2. Why did Anthony keep the fish he had bought in the aquarium for two days before starting his investigation?

3. Why did he use two jars of the same size, put the same amount of water in the jars, and place three fish in each jar? Was it necessary that the conditions in the two jars be the same at the beginning of the experiment? Why or why not?

4. Why did he put ice cubes in only one jar? Why not in both jars?

5. What did Anthony want to find out from this experiment?

B. Use the following terms about experiment.

a. Hypothesis – a possible solution to a problem or a possible explanation of a phenomenon; ex: Anthony’s hypothesis was that the fish in the aquarium died because of the sudden drop in the temperature of the water.

b. Experiment – an activity specially designed to test if a hypothesis is right or wrong.

c. Variable – a particular aspect of an experiment that may be changed. Ex: temperature of the water where the fish live.

d. Experimental setup – the set up where one variable has been changed; Ex: Jar No.1

e. Control setup – the setup identical to the experimental setup except that no variable has been changed; Ex: Jar No. 2.