I usually go to the internet as well, it is a saviour! We have a nightly routine where the girls get to ask me one more question before they go to sleep and I get some really tricky ones! Chloe asked me what is behind the clouds, Jasmyn told her that God was behind the clouds. Ah, Catholic Primary Schools, they certainly teach them the facts!! Good luck...it only gets harder the older they get, start your science degree now!!