Fair testing (age 9+)
Use test results to make predictions and set up further comparative and fair tests to investigate new questions
What a learner can do afterwards
- Use results from an investigation to make a specific, testable prediction
- Design a follow-up test to check the prediction
- Explain the reasoning linking the original results to the new prediction
1 · Read
You have used results to answer a question. Now use a pattern to predict a new result and plan a test to check it. A prediction names an outcome you can measure or observe. A rising or falling pattern may suggest more or less next time, but it does not guarantee what will happen.
In Ben's test, the 100 mL plant was taller than the 50 mL and 150 mL plants. Ben predicts that 125 mL daily might give a height between 7 and 10 cm after two weeks. The 125 mL amount lies between the water amounts that gave those heights. This is a possible outcome to test, not a known result.
For a fair follow-up, compare 125 mL with 100 mL and 150 mL in the same new test. Use several beans for each amount. Keep bean type, starting height, soil, pot size, light and growing time similar. Only daily water amount should change on purpose. In other tests, keep the conditions that could affect your measurement the same.
A result inside your predicted range supports the prediction for that test. A result outside the range does not match it. Check the measurements and test conditions, then repeat. Use the new evidence to keep or change your prediction. One match does not prove a pattern always works.
You can extend a steady number pattern as a prediction. Ramp heights of 5, 10 and 15 cm gave roll distances of 12, 24 and 36 cm. Each extra 5 cm added 12 cm to the distance. Predict 36 plus 12, or 48 cm, for a 20 cm ramp. Then test whether the pattern continues.
Explain the evidence behind your prediction, test it fairly, and compare the new results with what you expected.
From one test to another and its accompanying flashcards are original material written for this dataset.
More to read
From one test to another
A material's properties are things you can observe or measure. You could investigate how much water passes through paper covers.
Imagine comparing one paper layer with two layers of the same paper. An adult seals the covers across identical open rings above collecting cups. The seals stop water flowing around the edges. The adult pours 20 mL onto the centre of each cover and collects the water passing through for one minute.
In this example, 12 mL passes through one layer and 7 mL through two layers. The adult measures the collected water in a measuring cylinder. These are made-up results for practising how to plan a follow-up.
The lower amount with two layers suggests a prediction: three layers might let through less than 7 mL in one minute. A new test must check that prediction.
Compare one, two and three layers. Keep paper type, covered area, seals, starting water amount and timing the same. Use fresh dry paper for each trial and repeat each layer count. Check for leaks around the seals. Compare the measured volumes with the prediction, including any results that do not match.
2 · Watch
Take it off screen
Where it sits
Where this leads
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.