I have multiple activities and multiple categories, i need a form that allows entry of this data

I remember from my past QB knowledge that I have done this before, but its been awhile. So I create one table of the 10 activities, and one table of 10 categories, and both tables would be children to the parent intermediary table of activity categories? 
I don't have access to my previous apps to see how I constructed this so I'm still a  bit lost.
By doing the proposed method, the user would utilize the intermediary table and select an activity and select a category and then input the numerical value into that selection. This would seem to work.