I like my TA to listen so she understands my modelling and expectations. She also keeps an eye on those who may need things repeated quietly. However, in a situation where I need to be seen to be using her 'more effectively' I give her an observation sheet to monitor a child's behaviour during a certain amount of time. When asked I usually say that I want to make sure any problems with following instructions, not listening,distracting fiddling or whatever can be ruled out so I know the next step in trying to help this child progress further. Usually works. I play the game.