The more prior knowledge the children know the more they are going to understand that topic. But first, teachers need to know how much knowledge their students have on a certain topic before doing a lesson centered around that topic. One technique that is being suggested is know as word association. Word association is easy to implement and can provide teachers with information essential to their instructional planning and teaching. Word association is a means of measuring children's knowlege about a topic by examining what words they can associate with it.
Children simply have to write down all the words that associate with that one word.
The teacher can tell how much they know on that topic by the number of words they have written down. The only draw back is that teachers might begin scoring students differently. Otherwise this is a very good tool for finding out knowledge on specific topics.