Just as your science teacher dismisses you for the day, she tells you that you are going to study animal and plant cells next class.

She assigns you five pages of reading and note-taking for homework. You already have quite a bit of homework to do for your other classes, so when you get home, you wash-up and start your homework right away.

You turn to the new chapter in the textbook, and begin to read and take notes.

After one hour, as you try very hard to stay awake, your head begins to get heavy. Your eyes are closing on you ...