Define the independent and dependent variable:

A researcher was interested in finding out whether talking to plants was related to plant growth. To test this idea she used 20 plants where all 20 plants had the same amount of food, water and sunlight. She randomly assigned the 20 plants to 1 of 2 groups: she talked to 10 of the plants for 1 minute/day; she talked to the other 10 plants 10 minutes/day. Every day for one month the researcher measured the height of the plants.