Did you know the human body is 60% water?  Water has a big impact on performance and success in school. When we do not drink enough water, our body works harder, blood flow decreases and our mind is not as sharp and quick.  Daily fluid intake (total water) is defined as the amount of water consumed from foods, plain drinking water, and other beverages.  If you wait, it's too late - use thirst as your guide, and drink water when feeling thirsty to maintain the proper hydration.  Daily fluid intake recommendations vary by age and gender, but general guidelines are an average intake for men of 10-13 cups of total beverages/day and for women, 9-10 cups of total beverages/day. Although daily fluid intake can come from a variety of foods and beverages, plain drinking water is the best way of meeting daily fluid needs since it has zero calories.  Other beverages can be high in sugar and unneeded calories and do not offer any nutritional value. 

Some of the major functions of water in the body are maintaining the proper balance of nutrients and electrolytes (calcium, sodium and potassium), regulating body temperature and keeping you cool, lubricating your joints and bones, flushing out dirt and germs from your body and providing optimal conditions for brain power and physical performance.   Brain power and mental capacity has been shown to increase upon drinking water when thirsty, and for optimal performance during physical activity, water is major regulator for the body.  The common conception that sports drinks need to be consumed when exercising is a myth.  Water is the best drink to consume during exercise and physical activities.  If one is participating in vigorous, intense workouts that last longer than 60 minutes, then a drink with additional carbohydrates (sugar) and electrolytes (calcium, sodium and potassium) is beneficial to replenish lost nutrients.  A good guideline to follow is during workouts or physical activities, drink ~1/2 cup of water every 15 minutes (1 hour workout = 2 cups or 16 ounces)

http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/water/art-20044256

 https://www.sportsdietitians.com.au/wp-content/uploads/2015/04/Fluids-in-sport.pdf

http://www.livestrong.com/article/409715-why-is-water-important-in-a-balanced-diet/

 "Supported by the Statewide Health Improvement Partnership, Minnesota Department of Health and Dakota County Public Health Department"