A scientist wonders whether plants grow better when music is played for them. He designs two soundproof rooms with the same amount of light each day, the same humidity, and the same size. In each room, he plants 25 plants in individual pots; the plants are all the same age and size and given the same amount of soil and water. In one room, he puts a music player and plays classical music for 24 hours a day for a month. In the other room, no music is played. At the end of the month, the scientist measures the height of each plant and records it in his data book.