WLCSP
This package is very small and cheap to produce. It also has benefits due to the lack of bond wires. Bond wires increase parasitic inductance, and can be a problem for high speed designs.

The downside is that they are very tiny!

The last 5 layers of the Skywater PDK define the layers necessary to build the WLCSP package.
Course feedback
I think project based learning really helped. I can read a text and then recall, I've done this before, I've done this in Matt's course
Liyue (digital course)