Carrell & West (2010)
Does professor quality matter? Evidence from random assignment of students to professors
J Political Economy 118, p409

-USAF study showing a negative correlation with learning

Hessler et al (2018)
Availability of cookies during an academic course session affects evaluation of teaching
Medical Educ 52, p1064
doi: 10.1111/medu.13627

- you need to laugh about it all!