Predicting what happens next
Computer Science · Key Stage 1 · The School
Predicting is not guessing
A guess is a stab in the dark. A prediction is different. You trace each step, one at a time, and work out what must happen. If you trace carefully, your prediction should match the real result. That is what makes it thinking, not luck.
Tracing step by step
Start with 3. Add 2. Add 2 again. What is the answer? Do not jump to the end. Trace it: 3, then 5, then 7. Each step changes the number by exactly one amount. Follow every step and the answer becomes certain, not guessed.
Checking your own prediction
After you predict, always check. Run the steps for real, or work them out again slowly. If you were right, your tracing worked. If you were wrong, look for the exact step where your prediction and the real answer split apart.
Tracing a robot's moves in your head
A robot starts facing north. Steps: forward, turn right, forward, turn right, forward. Before running it, trace each step in your head. Facing north, move forward: still facing north, one square up. Turn right: now facing east. Forward: one square across. Turn right: now facing south. Forward: one square down. Predict the final square and direction, then run it to check. If your trace was careful, the robot lands exactly where you said.
Why predicting matters
Predicting first means you understand a sequence before you see it run. It also means you notice straight away if something unexpected happens. Without a prediction, a surprising result just looks normal, because you never said what you expected in the first place.