Scientific method. Exercises

Scientific Method Exercise

Choosing Hypotheses

1. A scientist has 12 plants. All the plants were the same kind and about the same size. He put three plants on a window sill inside a room. He put another three plants in a closet without a light. He put another three more plants outside on the ground. He put his last three plants outside too, but covered them with paper bags that had wholes punched in them for air. All the plants were given good soil and enough water. The plants on the window sill and the plants outside in the open grew well. The plants outside in the bags turned yellow and grew badly. The plants in the closet died. Which of the following is the best hypothesis based on the facts?
a) Green plants turn yellow due to disease.
b) Green plants don’t live for very long.
c) Green plants need light to grow.
d) Green plants cannot grow inside
e) Green plants grow well in closets.

2. Louis Pasteur, a famous scientist who lived over 100 years ago, made an important hypothesis about a certain germ called bacteria. He noticed that bacteria grew quickly in open jars of liquid, like chicken soup. Bacteria also grew in jars of soup that were sealed tightly so that no air could get in. However they didn’t grow in soup that was sealed tightly in a jaw, then boiled and kept sealed after it cooled. When was Pasteur’s correct hypothesis?
a) Bacteria cannot grow in jars.
b) Bacteria must have air to survive
c) Bacteria only grow in chicken soup
d) Bacteria can be killed by boiling.
e) Bacteria can live in boiling liquids.

Errors in experiments

Tell what is wrong with each of these experiments. Choose from this list:

· Not enough subjects
· Subjects were not similar.
· Conditions were not kept the same
· The experiment was not reproduced.

1. A gardener wanted to know if XYZ fertilizer would be good for this vegetable. He fertilized all his bean plants with XYZ but didn’t put any fertilizer on his pepper plants. His beans didn’t do well at all, but he got a good crop of peppers. He concluded that XYZ fertilizer was no good.

2. Alice Larsen wanted to see if a new premium gasoline would give her more kilometers to the liter. She filled her car with the new gas and went on a long trip. When she figured her mileage, she discovered that she has gone 40 Km farther on this tank of gas then she went on a tanks of regular gas when she was driving around town as usual. She decided to buy the premium gas for then on to get better mileage.

3. A molding machine in a factory was not working very well. About a third of the time, the plastic squirt guns that it was making come out with a flaw in the handle. The repair mechanic adjusted the stamping pressure. Then she ran one gun through. It came out just fine, so she figured she had solved the problem.