Why is it important to annotate a text?
will give

It's important because if you don't you won't understand as much, it's like taking colorful notes! If your notes are bland you won't understand as well.

onto a large boat, and mark the water level that the boat sinks to. then, take the elephant out and put a bunch of marked weights onto the boat until it reaches the same water level. add up the masses of the weights to get the weight of the elephant.