# 01Setting up electrical loops

Ee01TA of the Electricity and Energy topic
• ## 01 Think again! – about electric circuitsEe01TAnugget01 Activity

### Questions to review current thinking, to provoke thought and discussion

What the activity is for

These diagnostic questions are used for two main reasons:

• To encourage students to talk and think through their understandings of electric circuits.
• To provide the teacher with formative assessment information about the students' understandings of electric circuits.

What to prepare

• printed copies of the questions, on the support sheets

Support sheet

What happens during this activity

These questions might be used right at the start of the first lesson. Who can get them all correct? It would be a good idea to get the students to work in pairs on the questions, encouraging each pair to talk through their ideas. Collect responses from all of the pairs and discuss in a whole-class plenary.

Alternatively, the questions might be set for homework prior to the first electricity lesson, so that you have time to read through the responses.

The questions review key points from the SPT: Electric circuits topic.

Question 1

Two bulbs: both bulbs lit with the same brightness because the electric current is the same everywhere in the circuit.

Question 2

Small and large resistance: the current gets less but not zero because the battery cannot push as big a current through a larger resistor.

Question 3

Resistors in parallel: the current is greater because the total resistance is now smaller (because the second resistor provides an extra path for current).

Question 4

Best word: electric current; electric charge; voltage; energy; power output.

• ## 02 Questions about circuits with series connectionsEe01TAnugget02 Activity

### Questions to promote discussion and thinking

What the activity is for

These diagnostic questions are used for two main reasons:

• To encourage students to talk and think through their understandings of electric circuits.
• To provide the teacher with formative assessment information about the students' understandings of electric circuits.

What to prepare

• printed copies of the questions, on the support sheets

Support sheet

What happens during this activity

It would be a good idea to get the students to work in pairs on these questions, encouraging each pair to talk through their ideas. Collect responses from all of the pairs and discuss in a whole-class plenary.

Alternatively, the questions might be set for homework prior to the lesson, so that you have time to read through the responses.

The questions review key points relating to series circuits.

Question 1

The battery potential difference is shared between two resistors connected in series: V1 is 4 volt; V2 is 5 volt; V3 is 4 volt.

Question 2

The potential difference across the resistors connected in series is in proportion to their resistance (big resistance: big potential difference). V1 is between 3 volt and 6 volt: the larger share across the larger resistor.

Question 3

Same reasoning as question 2: V1 is B; V2 is D; V3 is D; V4 is B.

Question 4

The potential difference between a and b is zero because there is no resistance between these points, and the potential difference across R is 3 volt. With the switch open, the ammeter reads zero and the voltage between a and b is now 3 volt (The voltmeter is in effect measuring the potential difference across the supply).

• ## 03 Questions about circuits with parallel connectionsEe01TAnugget03 Activity

### Questions to promote discussion and thinking

What the activity is for

These diagnostic questions are used for two main reasons:

• To encourage students to talk and think through their understandings of electric circuits.
• To provide the teacher with formative assessment information about the students' understandings of electric circuits.

What to prepare

• printed copies of the questions

Support sheet

What happens during this activity

It would be a good idea to get the students to work in pairs on these questions, encouraging each pair to talk through their ideas. Collect responses from all of the pairs and discuss them in a whole-class plenary.

Alternatively, the questions might be set for homework prior to the lesson, so that you have time to read through the responses.

The questions review key points relating to parallel circuits.

Question 1

The potential difference across both resistors in a parallel circuit is the same, irrespective of resistance (the current through each resistor is different).

Question 2

This is just the same as question 1.

Question 3

When the switch is closed, the ammeter reading stays the same, as does the bulb brightness. This is because the potential difference across B1 stays the same.

Question 4

A1 is 2 ampere. A2 is 1 ampere (current equal in equal arms);

A3 is 6 ampere and A4 is 4 ampere (current inversely proportional to resistance. Big resistance, small current);

A5 is 4 ampere (current inversely proportional to resistance) and A6 is 5 ampere.

• ## 04 Current and potential difference laddersEe01TAnugget04 Activity

### Getting a feel for relative values of quantities

What the activity is for

Here you can impart an idea of the relative values of different currents and potential differences. Having an idea of these values for different sources and processes allows the units ampere and volt to acquire meaning, and enables the values derived from calculations to be checked against an internal model of what is reasonable. The ladders are one–dimensional graphs, used often in the SPT14–16 topics to support quantification, putting the value of any physical quantity into a context.

What to prepare

• appropriate scale prints of the support sheets provided
• cut out values and items from the support sheets, if these are to be used
• some Blu–tack

Support sheet

What happens during this activity

The support sheets are provided in several formats so that you can use them in a number of ways.

You could provide a blank ladder at a large scale on the laboratory wall, and add values to it over the duration of the topic as you encounter these values.

You could provide a completed ladder, adding your own values to it as these come up in the conversations in the class. These could be stimulated by distributing a range of research questions to groups within the class to populate the values.

You could provide a blank ladder to a group, together with at least the objects and processes provided, and ask them to agree on how to place these items. Groups might then usefully compare their placements before being given the matching values, and so reordering their values, or you might provide the unmatched values and objects/processes, only placing them on the ladder afterwards.

Placing about five items on such a ladder produces a manageable demand.

• ## 05 Simple measurements and calculationsEe01TAnugget05 Activity

### Anchoring quantities in student actions

What the activity is for

Making measurements gives a real connection to the quantities involved.

What to prepare

• some cells and batteries, 1.5–6 V
• some electrical wires
• a well-designed ammeter
• a well-designed voltmeter
• a collection of lamps and resistors to match the batteries and meters
• printed copies of the support sheets

Support sheet

What happens during this activity

Introduce a number of circuits where the goal is to find the effective resistance of the circuit. Students need to choose where to put the ammeter and voltmeter, and then transfer their choice and readings to the calculations templates. As with writing templates, the idea here is to encourage good practice and that students should eventually lay out their calculations by themselves. The templates are there to act as prototypes of clear communication.

There are extensions that could be made, from seeing if the resistance stays constant as the potential difference is varied, to finding the resistance of separate components in the circuit. However, no circuits much more complex than these are appropriate at this level.

• ## 06 Present an interactiveEe01TAnugget06 Activity

### Provoking discussion around a screen

What the activity is for

Children revisit and review their ideas developed by earlier teaching by using an interactive from the SPT: Electric circuits topic as a presentation support.

What to prepare

• a selection of interactives chosen from the SPT: Electric circuits or SPT: Electricity and energy topics
• a clear set of tasks and timescales, appropriate to the small groups within the class
• some real circuits to compare the models with some physical rope loops

What happens during this activity

Children use the interactive to explain what's happening in the circuit – they provide the voice-over. It will be important to establish the need to get a full commentary on the interactives – more than: There you are, it's obvious. You could increase the demand by setting one or a small group of children to make a screencast/video podcast of the action, but this might best be done in small groups around the computers, with children taking it in turns to be the explainer, using physical models, animations and the real circuits. They should be encouraged to make real efforts to relate the physical model, the animation and the circuit and to use this relationship as an explanation.

• ## 07 Calculating for understandingEe01TAnugget07 Activity

### Exemplifying good practice – students have something to copy

What the activity is for

There are many calculations to do in making predictions for electric circuits. These involve quite a few quantities.

What to prepare

• a well practised hand on the board, together with some calculations that you have run through beforehand – it's not easy doing these live in front of a class
• a number of relationships, carefully laid out with their units (These are the toolkit, each tool to be selected and used as needed. Don't be caught out using a hammer where a screwdriver is appropriate.)

Support sheet

What happens during this activity

Select things to be calculated where you are confident that you can explain the strategy – linking each line of calculation to the final goal. That means tuning what you do to your own confidence and to the abilities and aptitudes of the class. Do try to avoid just listing the quantities and then guessing which tool is appropriate. The calculations should be a part of an explanatory story that's being woven about the circuit.

Some rules of thumb to help this to come true:

• Don't hurry.
• Always refer to a diagram of the circuit where the loop in which you're working can be identified.
• If dealing with only a part of the loop, redraw only that part and mark in the quantities explicitly.
• Always write down the relationship, then substitute in values with units, then evaluate.
• Never use raw numbers: it's physical quantities that you're dealing with and they consist of number and unit. (This is using quantity algebra, and it is strongly recommended as a means of clarifying and checking thinking throughout.)
• Base everything on only a few relationships.
• It bears repeating: don't be tempted to hurry.
•