A brief summary of selecting visual representations for teaching.

In this summary, adapted from my upcoming book, "The Expert Teacher". I look at how teachers choose to represent and augment the ideas being taught can help and hinder student understanding. This vital part of our teacher expertise is therefore a part part of our pedagogical content knowledge,

Visual representations or illustrations can foster an understanding that words alone can’t manage. They are helpful by

• engaging curiosity and empathy,
• helping teacher clarity,
• creating a context for learning,
• elaborating on or highlighting specific aspects of an idea,
• helping to organise written information.

We have five, distinct, purpose types of visual representation we can use. (see Mayer and Gallini 1990; Carney and Levin 2002)

Type of illustration	Definition	Examples
Decoration	Images that are not directly related to the content.	A picture of Windsor Castle when talking about the monarchy.
Representational	Show one useful element.	A drawing of the tissues of a leaf. A diagram showing the layers of the earth.
Organisational	Show the relationships within the content.	A timeline of the events during the Cold War. A table to compare and contrast plant and animal cells.
Explanation/interpretational	Show how the system works.	An illustrated sequence of words and pictures that show how to perform a task. A weather map.
Transformational	Images that make the material more memorable.	A labelled diagram of an avocado representing the proportional sizes of the layers of the earth.

Be aware each type does not have the same value when it comes to ensuring student understanding.

The methods of showing students information “non-linguistically” range from symbols to graphic organisers, to computer simulations, to hand drawn sketches and diagrams, to info-graphics and pictures and photographic images. Teachers commonly supplement their talk with images , and rightly so: if an idea is shared both verbally and with an image, the likelihood of the idea being learned is better retained .

Strong learning occurs when words and images are combined . It is the combination of a well-selected image with decent labeling and a honed teacher explanation that helps to ensure that students begin to understand the new information being shared. Considering the ubiquity of the slide show presentation as the interface of choice (or management diktat) between teacher planning and student experience, we must give great thought to how the ideas and concepts are represented. It is the capacity of the slide show to be a repository for a teacher’s whole lesson that makes them attractive: everything can be sequenced so the lesson will flow (allegedly). However, in this large scale lesson slide show, a teacher can get lost while searching for appropriate and quality images for the students to interact with. As can a student. If an image is too complex and requires too much ”reading” students will not be able to assimilate all the information. We must therefore think about what makes a quality image.

What does research tell us about choosing useful visual representations?

Visual representations might be best used when teaching more complex ideas since our visual system is better at dealing with complexity than our linguistic system . When ideas are complex, seeking an image to simplify them is a useful technique: illustrations can help to highlight differences between ideas and spatial relationships and can help us to isolate individual components of a broader idea or concept. However, not all forms of image lead to the same degree of understanding. Illustrations that are too realistic tend to provide ancillary information that can obscure the central idea we are trying to communicate. In terms of developing understanding, simple line drawings can often be the best solution at an early stage and may form a decent basic representation of knowledge before we move on to more complicated and realistic representations as the students’ knowledge grows.

So in selecting an image teacher must be aware that:

• students perform worse on retention tests when images are merely entertaining or decorative, (which seems like a classic case of engaging students in tasks rather than concepts.)
• images that have been designed to improve motivation and interest in topics have also been shown to be ineffective
• although novel images are great for drawing student attention, they suffer when used too frequently.
• selecting images with a suitable level of complexity not only gains students’ attention but also holds it rather better than a more simple image
• images that show how a system works lead to cognitive interest (rather than emotional interest) and are therefore more useful when we are attempting to develop students’ understanding.
• images that are too elaborate can be problematic as they may be too difficult to read or might be interpreted in too many different ways by the students to support the ideas being taught. As always here, we must consider what our students already know and what they can do, and we must maintain the development of student understanding as the central factor behind our image choice.
• although providing a picture may help factual recall, it can diminish the student’s ability to describe the overall purpose of a text.
• location of the image also makes a difference: a picture that comes after the text may improve the comprehension of the information in the text better than a picture placed before it.