☰ Year plan · Science

Tiny plastic, precious water, and where it is

Week 18 · Theme 3 Protecting Our Planet, Unit 3 Our Earth’s Resources, Concept 3.1 (C) and Concept 3.2 Water as a Valuable Natural Resource (A) · 3 lessons
2

Why water is precious

Discovery Education Science P5: Term 2, Unit 3, pp. 30–35
GoalDescribe how water is used in Egypt and at home, work out how much water everyday jobs use, and choose ways to save it.
New words
natural resource · something from nature that people use, such as water, wood or oilconserve · to use carefully so that less is wastedagriculture · growing crops and keeping animals for food
Explanation

A natural resource is something from nature that people use. Water is one of the most valuable. We drink it, cook with it, wash with it and use it to grow food. In Egypt almost all our water comes from the Nile. Farms use a large share of it. At Aswan the High Dam holds the water and helps to make electricity. In desert oases such as Siwa and Kharga, people use groundwater from wells. We cannot make new water, so we must use it wisely. Ordinary jobs use more than we think. A running tap uses about 6 litres a minute, a shower about 10 litres a minute, and one flush of a toilet about 6 litres. These numbers are rounded, but they help us compare. A short shower and a tap turned off while brushing save many litres a day.

JobAbout how much water
brushing teeth, tap running 2 min12 L
brushing teeth, tap off1 L
5-minute shower50 L
one toilet flush6 L
Worked examples
ShowerMinutesWater (L)
long550
short330
Compare two showers. A 5-minute shower uses about 5 × 10 = 50 litres. A 3-minute shower uses about 3 × 10 = 30 litres. The short shower saves 50 − 30 = 20 litres.
one flush: about 6 L20 flushes a day
Farida’s family flushes the toilet about 20 times a day. Each flush uses about 6 litres, so they use about 6 × 20 = 120 litres a day for flushing alone.
water at noon✗water in the evening✓mend a dripping tap✓
Smart choices. Watering plants in the cool evening saves water because less evaporates than at noon in the hot sun. Fixing a leak saves water, too.
Class activity

Tap flow test (a grown-up helps). Open a kitchen tap gently and time how many seconds it takes to fill a 1-litre jug. Work out the litres a minute: 60 seconds divided by your time. Then work out how much water the tap would use in 2 minutes while you brush your teeth. Pour the water on a plant afterwards.

Practice
1
Name three ways water is used in Egypt.
2
A shower uses about 10 litres a minute. How much does a 4-minute shower use?
3
A dripping tap wastes 3 litres every hour. How much does it waste in 12 hours?
4
Does each action save water? (a) turning off the tap while brushing, (b) watering plants at noon in the sun, (c) mending a leak.