Estimation is an important skill that we all use every day, often without realizing it. It might not seem very scientific, because we think of science as being accurate and precise—surely estimating is just a form of guessing. It seems unpredictable and unreliable, but actually, many scientists use estimation in their work. In many cases, things could be measured or counted accurately, but sometimes it is simply more practical to estimate because collecting accurate results would be too time-consuming and too difficult. This is the value of estimation. The following exercises are fun and interesting ways of teaching estimation.