Compact way to display weekly schedule?

So, basically I need to display the weekly schedule for classes. I would like this to be quite compact, so I want to just show if the class runs in the morning/afternoon/evening for each day (I will determine the actual time ranges at some point).

So that means, if arranged in a grid, there are 21 cells (see attached image). I'll probably include the actual times on mouseover/click in a tooltip, eg 14:00 - 16:00.

There must be a more efficient/compact way of displaying this information than a grid of 21 cells, surely? If anyone has ideas/experience, please do let me know. Thanks.

EDIT: For a bit of context, this needs to be compact because I am displaying these courses as search results, so I need some kind of system in place as a "quick overview" of what the scheduling is.