As soon as you're visually aware as a child you'll start to see images... On television, on computer screens, in newspapers, books and magazines and you'll be presented with images that generally conform to the rule of thirds. If you're still unsure what the rule of thirds is and how it's used in photography and paintings - type 'Rule of thirds' in Google and you'll see thousands of examples.
Generally when I initially explain it I use as an example one of Thomas Ruffs deadpan portraits.
These image conventional compositions with the person sitting in the central third with the eyes falling on the top third intersection. Look through historical paintings and most portrait photography these conventions generally apply. Given a camera and told to take a photograph someone - most people will apply these rules. So when deconstructing your research images and analysing them, this is one of the basic things you can discuss in your work. Do the images you're looking at stick to these conventions or break the rules? If the image doesn't conform to the rule of thirds - why do you think it doesn't - what is the photographer trying to do?
Think about the space that's possibly been created, think about the use of the image - is the space there to provide space for text perhaps?
Breaking the frame
Look at your research images and look at the key subject in the image or the main components - do any of them break the frame or are all the elements of the image contained nicely within the frame? If they do break the frame as in the sheep here in this famous painting by William Holman Hunt 1852 "Strayed Sheep" at Fairlight in Sussex. Why?
A lot of fashion Photography despite the fact that it is constructed and planned includes this aspect of composition - why? Look at fashion images and you'll see limbs and parts of bodies cut off by the frame of the image - do you think this right or wrong - does it matter, do the limbs need to be in the image? Are there rules for instance when you shoot someone standing up about where you should cut through their legs when shooting the image as a 2/3rd or 3/4 length portrait?
When and why might you leave space in a picture? Why do we shoot portraits as upright compositions, why is that the right way? Similarly why are most landscapes horizontal - and what if we use a square format camera - how does that effect the composition and the balance of the image? What are your thoughts on the matter? See this article here.
Look at the images that you're researching or analysing and discuss them in these terms.
How big in the frame?
Looking at the image what can you say about the way the 'Subject' is framed, is it close or far away - why? Would it affect the way that we read the image and make sense of it if the subject was closer or further away. What is the relationship between the subject and the background or surrounding subjects?
If there is more than one person in the frame - how have they been composed in relation to each other? The space between the people - what does it suggest about their relationship?
Where has the photograph been taken from - again this is very significant when it's in conjunction with the image of people. Has the photographer shot the image on the same eye-level as the subject? How does this affect the reading of the image - what does it suggest about the relationship between the photographer and the subject?
What if the photographer is higher than the subject - how does this affect the psychology of the image and the opposite... the photographer is lower than the subject? All of these things have a very significant bearing on the way the images are perceived.