Look at these dry seeds. What do you think they need before they can grow into healthy plants?

Hands up one idea. We will turn one of your ideas into a real test today.

Soil and warmth matter too, but today every group will test either light or water so the class can compare fair results.

Listen to this short model. I wonder whether cress grows better in light or in the dark. I predict the windowsill cup will look greener and healthier because plants use light to make food. The dark cup may look pale or yellow.

I change only the light. I keep the same seeds, cotton wool, cup and water. I check over the coming days, because plant tests are watched over time, not finished in one afternoon.

In your group, choose one factor to test: light or water.

Five cards appear on the board: amount of light, amount of water, how healthy the seedlings look, type of seed, and amount of soil or cotton wool.

First we sort them for a light test. What do we change? What do we measure? What must we keep the same?

Then we flip the cards for a water test so every group sees its own path.

Before anyone moves, we agree the places together: bright windowsill for light cups, dark cover or cupboard for dark cups, and one shared sill for all water-test cups.

Watch one labelled pair set up at the front first, so everyone sees matching amounts and a clear single-factor change.

Now set up the test your group planned.

Place your cups only in the places we just agreed.