In an earlier post, you can read it here, I started talking about reading comprehension strategies and the book 'Teaching Reading Comprehension Strategies' by Sheena Cameron which has been very popular amongst South Australian schools of late.
There is no suggested order in which to teach reading strategies although research suggests students are 'cognitively ready to receive information on reading strategies when they are around 7 years of age. Students younger than this tend to have trouble thinking multidimensionally and also have difficulty in retaining strategies' (Cameron, 2009, p.21).
I've found that visualising is one of the easiest strategies to teach as children are usually doing it already as they read.  I'm just helping them name it and identify why it's important in helping them build an understanding of a text.  It is also important to help students understand that we all have our own unique way of seeing, influenced by our own experiences and prior knowledge.  There is no right or wrong, as the way I might connect to a text could be different from another person's because of our prior understanding and experiences. 

Visualising can be a very sensory experience.  The language used is similar.  Examples from the Cameron text (p.88) include -
'In my mind I can see ......
I can imagine .....
I can just taste the ......
I can feel the .....
I can hear the ......
I can smell the ......' 

Children who had been able to experience a variety of sensory play in early childhood will bring a rich vocabulary with them to school.  This is also why I think it is important that such play continues in school.

One activity I've used in class to teach visualising is to use these clue cards I'd collected from a Professional Development day.  They're not from the Cameron text which is good as a class might not have already used them but the source is unknown as it was just a photocopied sheet.  I love to know where they came from if anyone recognises them.  They're a great prompt but it would be easy to find other objects/animals to build clues around too.
Essentially the way this works is to provide the blank sheet to each student then read one clue.  You can find a copy of this template here.  Sorry I had to save it as a PDF rather than a Word doc.  It works best copied on to A3 paper. 
Have the students draw what they think it is in the first box on the left side of the page then read the second clue.  Do they still think it's the same thing or have they changed their minds?  Have them draw again then read the third clue.  Allow them enough time to draw again before then hand each student the picture card to stick in next to their work.

Here are some examples from the last class I did this with.  

There are seven different activites in the Cameron text.  One which is suitable for younger age groups is also available on her website'What is a nogard?'  takes you through a series of clues which the listener is meant to draw as they go. 

The description in The Gruffalo also works well if you mix it up a little. 

Next up in this series - activating prior knowledge.