Embarrassing - I think I figured it out but don't know a work around. The teacher stops showing up because the filter says "Values in range and null values". At that point her value is not in the range but it also isn't null - so she doesn't show up on the list anymore. Does anyone know any work arounds?
Hey Josh welcome to the forums! Your issue/question/problem will get more attention if you can post a packaged workbook or at least a bit of sample data. Tracy put together an informative guide on how to get the most out of your forum posts. I'm certain we can answer your question if we can better understand the problem you're facing.
So it sounds like you want your filter to act more like "show teachers who gave out demerits before this selected date." You can do this a couple of ways.
One option is to place your date field on the view and select Range of Dates. Then, choose the Ending date box and you'll be able to show only the dates up to the selected date.
Another option would be to create a date parameter and use it in a calculation similar to the following:
[Order Date]<=[Date Parameter]
Then, place that on the filter shelf and select True. Finally, show the parameter control to allow the user to change the date.
Hope this helps!