☰ خطة العام · العلوم (بالإنجليزية)

Saving water: an irrigation challenge

الأسبوع 28 · الوحدة الرابعة، المشروع بيني التخصصات «نظام ري حديث» · 3 دروس
3

Design a water-saving irrigation model

Science P6: Term 2, Unit 4, pp. 80–86
GoalPlan, build and test a small model of a water-saving irrigation system, then improve it.
New words
prototype · a small test model of a designtest · to try something to see how well it worksimprove · to make something better
Explanation

Engineers solve problems with a design process: ask what the challenge is, imagine ideas, plan and sketch one, build a model, test it and improve it. Here the challenge is to water a pot of soil with as little waste as possible. A grown-up can cut cups and tubing. You might use a funnel, plastic straws, a paper cup with small holes, tape, a tray and a measured cup of water. Sketch your idea first, because paper is cheaper to change than a model. Label each material. Then test: pour a measured amount of water and measure how much is held in the pot, how much runs off into the tray and how much is lost or spilled. Change one thing, such as slowing the flow, and test again. Share your design and what you learned.

Worked examples
Waterml
poured500
in the pot300
runoff in the tray150
spilled50
In a test, 500 ml of water was poured. 300 ml stayed in the pot, 150 ml ran off into the tray and 50 ml was spilled. The pot kept most of the water.
After improving the model by making the water flow more slowly, 400 ml stayed in the pot and 100 ml ran off. The change helped by 100 ml.
Habiba changes three things at once, so she cannot tell which one helped. Change one thing at a time.
Class activity

Irrigation model. With a grown-up, make a small model with the materials above. Sketch the plan first. Pour 200 ml of water, measure the runoff in the tray and write the result in a table. Change one thing and try again. Never use scissors yourself: a grown-up cuts.

Practice
1
Name the six steps of the design process.
2
Why sketch before building?
3
A model uses 200 ml and 120 ml stays in the pot. How much was lost or ran off?
4
Name one thing you could change in your model to waste less water.