Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity) :
the wind speed during a storm

Explanation

The wind speed during a storm can be estimated using a gas filled balloon. In figure OA is normal position of a gas filled balloon, when there is no wind. As the wind blows to the right, the balloon drifts to position B in one second. The angle of drift `angleAOB=theta` is measured, if h is the height of the balloon, then AB = d = `htheta` This is the distance travelled by the balloon in one second it must be the wind speed.