Yesterday our science teacher did a simple test for us. She put a white rose into a glass of water and added some blue chemical. (11) The next morning the blue color appeared in the top of the flower. She said the flower drinks through its lower part, (12) the color only showed us something that happens every day without being seen. (13), the useful part of the lesson was not the flower. It was that we had to wait a whole day and write down that nothing had changed at four o'clock. A scientist is not a person who finds things, (14) a person who keeps looking when there is nothing to see.
Many things in our home come from science. About one hundred years ago, a man in the USA invented the air conditioner, and before that people slept in very hot rooms in summer. (15) The production of these machines is not simple: workers must be skillful, and every part must be checked. Most of us never think about this, (16) we only notice a machine on the day it stops. (17), the same is true of the water that reaches your sink and the light above your notebook. Each one took somebody years to make safe, (18) none of them ask to be noticed.