Simplicity 

All the background is mainly white so you really

focus on paul and the equation he's doing up on the board.

Rule of Thirds

Sergio is to the left of the photo so that makes it the rule

of thirds.

Lines

The metal attached to the chairs forms lines.

Framing

the wallpaper above and the 2 kids frame that asian kid in the 

center of the picture.

Balance

This picture is an example of balance because

the background and everything balances the photo

out.

Avoiding Mergers

This picture is an example of avoiding mergers because 

the kid to the right's body is caught off.