20 questions
Thomas and Julie wanted to find out which material would insulate their teacher's coffee cup and keep the coffee hot for the longest period of time. They first wrapped her cup with bubble wrap and recorded the temperature of the coffee once every 15 minutes for 2 hours. They repeated the investigation, this time using newspaper instead of bubble wrap, but they got the same results for both materials.
What could they do to make sure their results are valid?
Repeat their experiment.
Use teas instead of coffee.
Use a different thermometer.
Conduct their investigation in a colder room.
Kevin wanted to find out which of his toy cars, the Corvette or the Mustang, would roll downhill faster. He made a ramp by putting several books under one end of a board so that the board was slanted.
Which would be the best way for him to perform his experiment?
Roll each car down the ramp separately five times and estimate which car looked faster.
Roll both cars down the ramp together one time and see which one gets to the bottom first.
Roll each car down the ramp separately one time, and time them with the second hand on his watch.
Roll both cars down the ramp together five times and record which gets to the bottom first each time.