Question

Michaela is conducting an experiment on the speed of toy cars on different

surfaces. For each trial, she uses a ramp covered in a different substance.
Michaela uses a different type of car for each trial to make sure it is free
from any materials from the previous trial. Michaela measures the distance
traveled and time of each car. Which of the following is a change Michaela
should make in her investigation in order to achieve more valid results?

Answer 1

D) Michaela should use the same type of car for each trial of her

investigation.

Step-by-step explanation:

Answer 2

She shouldn't use a different car each trial, it makes the results less valid. Instead she should use the same car, and should just clean off the car after each trial.