How much water should I drink?
Choose a body mass, the minutes of hard play and whether it is a hot day, and work out how much water a child needs in a day, in millilitres and in glasses.
Core concept
The body loses water in sweat, breath and urine, so a child needs about 35 mL of water for every kg of body mass each day, more when playing hard and on hot days
Topic: Our body and health
More than half of your body is water. Every day you lose some of it: in sweat, in the air you breathe out and in urine. You must replace it by drinking water and eating watery foods like fruit, dal and vegetables. A simple guide is about 35 mL of water for every kilogram of body mass each day. When you run and play hard you sweat more, so you need about 12 mL more for each minute of hard play, and a hot day adds about half a litre more. Feeling thirsty, dark yellow urine and headaches are signs that you need to drink. These numbers are a general guide, not medical advice.
What you will learn
- Explain why the body needs water every day.
- Work out a day's water need from body mass, play and weather.
- Convert millilitres to glasses of 250 mL.
Before you start
- Know that 1 litre = 1000 mL.
Materials
- A 250 mL glass and a water bottle
Equipment
- None
Procedure
- Record the water need of a 30 kg child who plays for 30 minutes on a normal day.
- Change to a hot day, and record.
- Change back to a normal day with no hard play, and record.
How this simulation is simplified
- About 35 mL of water per kg of body mass a day.
- 12 mL more for each minute of hard play, and 500 mL more on a hot day.
- A general guide for healthy children, not medical advice.