Communicating in science
Tables are one way we can show science information.

Physical concepts
Some lights don't use as much electrical power as others.

Nature of science: Communicating in science (tables)

Diagnostic and formative information
NOTE: This analysis of student responses comes from trials of the original task.
Most students seemed to be familiar with tables as a way of presenting information. In general terms they knew how to read the first table, although did not always interpret the detail well. Most of those who attempted filling in the second one were able to enter their responses in the correct place. A few, though, did not enter advantages and disadvantages into the separate columns, and a few did not differentiate between good and bad, putting them in the wrong cell.

However, there is also evidence that some students didn't use the table to answer questions, relying more on their background knowledge. This was particularly obvious in Question c). Year 8 students appeared to be less able to correctly answer this question than Year 6 students. One of the reasons appears to be that Year 8 students were more likely to be using the table to find the answers rather than relying on background knowledge, but often misinterpreted the data contained in it.  

The areas that caused difficulties were:

• Many students (including at higher levels) indicated that a disadvantage of low-energy bulbs was that they were dimmer than other bulbs. Three possible reasons for this response are:
  • They did not pay attention to the heading that indicated that the lights produced the same amount of brightness;
  • They interpreted joules as a measurement of brightness; or
  • This is an often-expressed opinion that students may have heard. Their personal theory about low-energy lights may have led them to ignore the information in the table.
• The term ‘joules" was unfamiliar to students, and it is not an expectation for most Level 2 students to have an understanding of this unit of measurement. However, many were still able to recognise that this was something to do with how much energy the light used.
• It was slightly more difficult for students to suggest an advantage for candles than a disadvantage, whereas the opposite was the case with the filament bulb. However, it was noticeably more difficult to give a disadvantage than advantage of low-energy bulbs.

• What story can we tell about the candles (light bulb, low-energy bulb) from looking at the table?
• What can we tell about how much energy a candle and a low-energy bulb use?
• The table doesn't tell us where candles or the bulbs get energy to make light. How do you think we can make them light up? How could we check our ideas? (These questions relate to what the table doesn't tell us but assumes we know.)

Science concept: lighting

Scientific vocabulary
Many students used the words power, energy and electricity interchangeably (as we are inclined to do in our everyday conversations). For Question b) about half of Year 4 students chose the candles as being best for saving energy. Over a quarter of these gave reasons that showed they interpreted energy as electrical power, therefore equating "saving energy" with not using electrical power.

Question c): The relationship between heat and light
Few students at Years 6 and 8 gave a complete answer for this question although many were starting to make a link to either the amount of energy used (usually) or (less often) the amount of light produced, for example:

• (The candle) uses fire. It doesn't use energy.
• (The candle) doesn't use power.

Older students were much less likely to give this sort of response.

 
Next steps 
Students need to know that some words we use in everyday conversation have a more precise meaning in science. Spend some time on developing science vocabulary to enable students to be more precise in their explanations. Practise using the right words in context as a quick game.

Misconceptions