Fair testing (age 9+)

Question 1

You tested two kinds of seeds to see which one sprouts faster. Both seeds were kept in the same light and given the same amount of water. After five days, Seed A had sprouted but Seed B had not. You now want to do another fair test to compare how the amount of water affects the two seeds. Which prediction is best based on your first test results?

Accepted Answer

Even with less water, seed A will still sprout before seed B.

Answer

Both seeds will sprout at the same time because they are getting the same amount of water.

Answer

Seed B will sprout before seed A because it needs less water.

Answer

Seed A will not sprout at all because it already sprouted in the first test.

Question 2

Mia investigated how the amount of water given to bean plants each week affects their height. She grew three groups of plants for four weeks, giving each group a different amount of water: 50 ml, 100 ml, and 150 ml per plant per week. At the end of the experiment the tallest plants were the ones that received 100 ml, the plants that received 150 ml were shorter than the 100 ml plants, and the plants that received 50 ml were the shortest. Based on these results, which prediction would be the most appropriate for Mia to test in a follow‑up investigation?

Accepted Answer

If the amount of water is increased from 150 ml to 200 ml per week, the plants will grow shorter than those receiving 150 ml, because giving too much water can hinder growth.

Answer

If the amount of water is decreased from 50 ml to 25 ml per week, the plants will grow taller than those receiving 50 ml.

Answer

If the amount of light is increased while keeping water at 100 ml per week, the plants will grow the same height as before.

Answer

If the amount of water is increased from 100 ml to 150 ml per week, the plants will grow taller than those receiving 100 ml.

Question 3

Sam tested how far a small toy car rolls down a 15‑cm long ramp when the ramp surface is smooth wood versus sandpaper. He gave the car the same gentle push each time. On smooth wood the car rolled 28 cm, and on sandpaper it rolled only 12 cm. From these results Sam predicts that if the ramp surface is made even more slippery (like a polished tile), the car will roll farther than 28 cm. Which of the following describes the best follow‑up test to check Sam’s prediction?

Accepted Answer

Use the same toy car, the same gentle push, and the same 15‑cm ramp angle, and compare the distance rolled on the polished tile surface with the distance rolled on the original smooth wood surface.

Answer

Use a heavier toy car on the polished tile surface and compare its distance to the distance the original car rolled on the smooth wood surface.

Answer

Give the car a harder push on the polished tile surface than on the smooth wood surface and then compare the distances rolled.

Answer

Measure how long the car takes to stop on the polished tile surface and compare that time to how long it took on the sandpaper surface.

Try three questions

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