When discussing anything at school with a group of enthusiastic children you could be tempted to go off track. There you are discussing a subject like Salvation and a child comes out with something. It may be a question or an observation but it is absolute gold! Unfortunately, often we have too much to cover in too little time and those pieces of wisdom are lost by the wayside as you bring the class back to your learning intention.
In order to stop losing these little nuggets of genius I use a 'Class Safe'. Luckily my Teaching Assistant has a fine art degree and he made this for me about of some cardboard!