• Quick retrieval from earlier learning (Series and parallel circuits). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. A parallel circuit has two branches. The current in one branch is 1 A and in the other is 1 A. What is the current from the battery, in A? → 2 APrompt: In parallel, the branch currents add up to the total current.
2. Adding more bulbs in parallel to a battery (each in its own branch) makes each bulb… (explode / go out / stay about as bright as before / get much dimmer) → stay about as bright as beforePrompt: Each branch gets the full battery voltage.
3. Series and parallel: which statement is NOT true? (In series, total resistance is the sum of the resistances. / In a parallel circuit, the voltage across each branch is the same. / In a series circuit, current is used up by each bulb. / In a series circuit, if one bulb breaks, the others go out.) → In a series circuit, current is used up by each bulb.Prompt: Is current used up in a circuit?

• Show a circuit with a gap and ask why the bulb doesn't light.
• Share the objective: Current and voltage rules in series and parallel circuits. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Two lamps are connected in series to a 12 V battery. The voltage across the first lamp is 8 V. What is the voltage across the second lamp, in V?
• Step 1: 12 − 8 = 4
• Step 2: So the answer is: 4 V
• Answer: 4 V
• Pause after each step and ask a student to say what comes next.

• Do these together. Students try each step on whiteboards before you reveal it.
• Use the hints as prompts rather than giving the answer.

1. Two lamps are connected in series to a 9 V battery. The voltage across the first lamp is 6 V. What is the voltage across the second lamp, in V? → 3 VPrompt: In series, the supply voltage is shared between components.
2. A 0.3 A current leaves a battery and splits into two parallel branches. One branch carries 0.2 A. What current flows in the other branch, in A? → 0.1 APrompt: Current is not used up; it is shared between branches.

• Students work on the student sheet. Circulate and check the first two answers of every student early.
• Students who finish: write a question of their own for a partner, with the answer.

The 8 questions are on the student sheet below, with answers in the key.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. Two lamps are connected in series to a 9 V battery. The voltage across the first lamp is 6 V. What is the voltage across the second lamp, in V? → 3 VPrompt: In series, the supply voltage is shared between components.
2. Two identical lamps are connected in parallel to a 6 V battery. What is the voltage across each lamp? (3 V / 0 V / 6 V / 12 V) → 6 VPrompt: A parallel circuit has more than one loop.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-8.