The investigative world of science

Every chapter of this book opens with a few questions under the heading Probe and ponder. They are not for any exam. They are there to make you curious. The very first ones: Why is one side of a puri thinner than the other? Are there more grains of sand on all the world's beaches and deserts, or more stars in our galaxy? Why does nature have such a huge variety of plants and animals? Then the book leaves a blank line for a question of your own.

Think about how you feel at a magic show. You know it is a trick, but you badly want to know how it was done. That itch to know is curiosity: the wish to know and to learn. Science starts there.

The book tells the story of your three years of science:

Ideas really do change. People once believed the Earth was flat. Careful observation showed it is round.

The book puts its aim plainly: *we don't want you to just learn new facts, we want you to learn how to find new facts.*

To investigate means more than looking and asking a simple question. You ask a focused question, plan a simple experiment that could answer it, and then use what you observe to improve your understanding. Doing that, you are an investigator, a young scientist. The puzzles can be small (why does dough rise?) or huge (is the world getting warmer?).

Two words are worth keeping apart. To discover is to find out something that was already there. To invent is to make something new that did not exist before.