How much water should you be drinking?

As we are outdoors more and temperatures are rising, it might be a good time to look at hydration. A healthy requirement for fluids can't really be the same for everyone.  Surely the amount of water that you need to drink has to do with the weather, your size, and how much you are exercising. In this activity student develop formulas for calculating their water needs, learn about the effects of too little water, and calculate what they should be consuming. The first 1:43 minutes of the following video could be a motivating beginning to this topic.

Next you could poll your students about how much water they think they should drink every day.