Sandra and Woo/WMG

There's more to this strip than meets the eye.
The first thing that strikes me as odd is that the recipient of the award in Sandra's dream is MRS. North. You'd think that this is Sandra dreaming of herself when she gets older, but why would she be called MRS. North?

This is because it's not just a dream to serve as the punchline to a joke. That was actually one of Sandra's memories of her mother before the latter passed away, hence why she wanted to make a name for herself in the field of math, and why the mere act of her not remembering a formula is depressing her so much (look at her face, it's not just disappointed, it's on the verge of tears.)