Lesson overview
Learning objectives
- Decompose a complex object into interacting parts.
- Model a mechanism using states and transitions.
- Write precise instructions that another person can follow.
Resources
- Cardboard box or diagram
- Sticky notes labelled panel, pin, drawer and magnet
- State-transition worksheet
Starter
Show a closed box and ask pupils to list every piece of information they would need before claiming to know how it opens.
Main activity
- Define a fictional mechanism with four components: left panel, right panel, locking pin and drawer.
- Assign states such as closed/open or in/out.
- Write constraints: the drawer opens only when both panels expose the pin.
- Create a state-transition diagram.
- Swap instructions with another group and test whether the sequence is unambiguous.
Plenary
Identify one instruction that depended on hidden knowledge and rewrite it.
Differentiation
Provide a ready-made state table for support. Extend by adding a false move that resets the mechanism or by writing a simulation.
Assessment evidence
A labelled decomposition, state model, tested algorithm and reflection on ambiguity.