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Diagnostic questions - a formative assessment tool

posted 30 Mar 2015, 07:47 by Mary Whitehouse   [ updated 30 Mar 2015, 08:18 ]
Many of the questions and tasks we have been developing in the York Science project  can be described as ‘diagnostic’. That is, they do not only tell you which students have some understanding of the idea we are thinking about, they also give you some information about the misconceptions of those who do not use the accepted scientific explanation.

For instance take a look at this question about how we see. 
What can you see in the dark?
The correct answer is D, but A, B, and C are all ideas held by many students (and adults).
  • Many children may have not experienced complete darkness and will know that after the light is switched off in the bedroom at night their eyes adjust to the dark and they can see dimly. 
  • They may have seen a cat at night and seen its eyes reflecting back the light from a torch or car headlights. The eyes reflect so well, it looks as though they are shining. 
  • Some children think that things that are shiny can be seen in the dark.

Evidence of understanding

In the Programme of Study for Science for Year 6 (10-11 years old) students are expected to be taught that we see things because light travels from light sources to our eyes or from light sources to objects and then to our eyes. So this question could be used in primary school to check that students understand this idea at the end of a sequence of teaching, or it might be used in secondary school prior to teaching ideas that further develop students understanding of light.

For all the diagnostic questions we develop we use the available research evidence to inform our writing. A good starting point for teachers looking for information about students’ ideas is the work of Ros Driver, including Making sense of secondary science , which includes useful bibliographies for each chapter.

Confidence grids

Rather than ask students simply to select one correct answer, where they may hold more than one of the ideas listed you can gain additional information by asking them how they sure they are about their answers.

A confidence rating grid like this can supply that information quickly.

When planning to use the question with a class, you need to think about what you will do next when some of the class give the answers A, B,  or C. Do you have a dark room you can use to show them that in complete dark you can see nothing? Or maybe the geography department will be taking them on a trip to some caves? (I am not suggesting you bring a cat into the dark room, or take one down the caves!) 
This item is one of the Evidence of Learning Items developed for the York Science project. The resource sheet and presentation are available in the Download section.

Mary Whitehouse is a member of UYSEG with an interest in secondary education and particularly in the relationship between teaching and learning and assessment. You can follow Mary on Twitter.