The shape of the lesson
By the end of the lesson, learners can
- Put the meter in the path: Connect the ammeter in series so the whole current flows through it.
- Direction and type: Conventional current and electron flow run opposite ways, and current can be steady or alternating.
- Current: a flow of charge, measured in amperes by an ammeter in series.
- Two directions: conventional current goes + to −; electrons go − to +.
- d.c. and a.c.: d.c. flows one way; a.c. keeps reversing.
One picture every idea returns to
Electric current is the flow of electric charge, measured in amperes by an ammeter connected in series. Conventional current is taken from positive to negative, while electrons drift the other way. Direct current flows one way; alternating current repeatedly reverses.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Charge on the move.. Flick a switch and a lamp lights at once. | Whole class, then pairs |
| 5 to 17 min | Teach and check: Put the meter in the path | Connect the ammeter in series so the whole current flows through it. Project tab 5 of the lab (Ammeter and voltmeter) and let a student drive it while the class predicts. | Whole class, then pairs |
| 17 to 30 min | Teach and check: Direction and type | Conventional current and electron flow run opposite ways, and current can be steady or alternating. | Think-Pair-Share |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 12 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Direction and type, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Think-Pair-Share
Pose the question, give thirty seconds of silent thinking, then a minute to compare with a partner before a few pairs share with the class. The silent minute is the part that cannot be cut.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| An ammeter is connected in series, not parallel, so the whole current passes through it. | Conventional current is taken from positive to negative, even though the electrons actually drift the opposite way. |
Electric current: worksheet
6 questions, 12 marks. Written in the style of the papers; no past paper question is reproduced.
State what is meant by an electric current, and name the unit in which it is measured.
A student wants to measure the current through a lamp.
(a) Name the instrument used.
(b) State how it must be connected in the circuit.
In a metal wire, the conventional current flows from X to Y. State the direction in which the electrons flow, and explain why this is different from the conventional current.
State the difference between direct current and alternating current, and give one source of each.
Two current-time graphs are recorded. Graph 1 is a horizontal straight line above the time axis. Graph 2 is a wave that rises above the axis and drops below it, again and again. State which graph shows alternating current, and give your reason.
A student writes, "An ammeter should be connected across a lamp, like a voltmeter, to measure the current." Identify the error and give the correct instruction.
Answer key and marking notes
- An electric current is a flow of electric charge. ✓
- It is measured in amperes (A). ✓
(a) An ammeter. ✓
(b) In series with the lamp (in the same line as the current). ✓
- The electrons flow from Y to X. ✓
- Electrons are negative and flow from negative to positive, which is opposite to the agreed conventional direction (positive to negative). ✓
- Direct current flows in one direction only; a source is a cell or battery. ✓
- Alternating current repeatedly reverses direction; a source is the mains supply. ✓
- Graph 2 shows alternating current. ✓
- It goes below the axis as well as above, which means the current reverses direction; Graph 1 stays one side, so it is direct current. ✓
- An ammeter is not connected across a component. ✓
- It must be connected in series, in the same line as the lamp, so the current passes through it. ✓
2 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
An ammeter is used to measure the current through a lamp. How should it be connected?
- Ain series with the lamp, so the same current passes through both
- Bin parallel with the lamp
- Cbetween the two terminals of the cell only
- Dit does not matter how it is connected
What is the difference between direct current (d.c.) and alternating current (a.c.)?
- Ad.c. flows in one direction only, while a.c. repeatedly reverses direction
- Bd.c. is always larger than a.c.
- Ca.c. flows in one direction only, while d.c. reverses
- Dthey are the same thing
Quiz key
An ammeter is connected in series so that the current through the lamp also flows through the meter. Connecting it in parallel (like a voltmeter) would not measure the lamp's current.
Direct current flows in one direction (as from a cell), while alternating current reverses direction repeatedly (as from the mains). The names refer to direction, not size.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.