If you intend to track attendance on a day by day, class by class basis, you'll need more tables and relationships to set up the appropriate links. A number of other users have gotten assistance with such an attendance tracking project so you may want to enter "attendance" into the search the forum box at top right and see what threads are found that might provide helpful examples.
I think you are asking about a conditional value list where selecting student level limits the topics listed to only those appropriate for the selected class level. If so, you may want to explore these links:
Forum Tutorial: Custom Value List?
Knowledgebase article: http://help.filemaker.com/app/answers/detail/a_id/5833/kw/conditional%20value%20list
Hierarchical Conditional Value lists: Conditional Value List Question
Feel free to post follow up questions here if those links aren't enough to get your value lists working correctly.