Look at these two ice cubes. If I leave one on the windowsill and one in a shaded corner, will they melt at the same speed?
How could we find out fairly?
Our question: Which place melts an ice cube fastest?
Our three places today: windowsill, shaded corner, and near the heater.
Predict which place will be fastest and say why. Predictions are the start of the science, not a guess to get right.
A fair test means we change one thing, measure one thing, and keep the rest the same.
Now we plan our test together on the board, sorting cards about our ice investigation into three bins: Change, Measure and Keep the same.
Help us sort each card into the right bin. Watch and talk first; keep your journal closed until we finish the board.
When every card is in place, copy the finished plan onto your Investigation Journal page so it matches the board.
Which place melts ice fastest?
Watch the class stopwatch on the board. We open it now, before any cube is set down. We start it together when every cube is in place, and we note the time when a place finishes melting.
We share three class places: windowsill, shaded corner, and near the heater.
Start by lining up your group's identical cups, one cup at each of the three places. When every cup is ready, we all start the class stopwatch on the board together, and after that you check your cups every 5 minutes, when we call the time. When a cube has melted fully, with no solid ice left, record the time it took. All the way through, keep cube size, cup and start time the same, because the only thing we are changing is the place.
We may not see every cube vanish. If time is up first, we stop together and rank the places by how much solid ice is left at that same clock moment. That is still a fair test.
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