Mosquito repellent is sprayed on one arm and the other arm is not sprayed.  The number of mosquito bites is counted after 2 hours. The INDEPENDENT variable is __________.

One grape is placed in tap water and another grape is placed in salt water. The change in their mass is measured after a day. The water is the ___________.

Two different cars are traveling at 60 mph.  At a certain point, both cars slam on the brakes.  The distance it takes for each car to stop is then measured. The different cars are the ___________ variable.

A stapler is used to staple 100 papers, it jams 5 times during the trial. A different brand of stapler performs the same test; it jams 22 times. The number of jams per trial is what type of variable?

Cockroaches are exposed to a pesticide.  After 3 hours, 95% of the insects are dead. What is the independent variable?

Two plants are grown using the same light and pots.  One plant is given water that has been microwaved and the other plant is given regular tap water.  Their height is measured after 2 weeks. The height of the plants is what variable?

An independent variable is...

An apple is cut into slices. Half of the slices are sprayed with lemon juice. All slices are stored in a sealed plastic bag. After 4 days, they are observed to see how brown they turned. The browness of the apple is what ___________.

Bacteria are grown in a petri dish. One side of the dish is sprayed with an antibiotic.  After a week, the number of bacteria colonies are counted on each side. The number of bacteria colonies are which variable?