I applied online. The process took 1+ week. I interviewed at Lehigh University (Bethlehem, PA) in Dec 2021
Interview
You need to provide a trial lecture and it's about 15-20 mins. You can pick a related topic and prepare for it in advance. It's a online presentation. And you can prepare slides for it.
It was an amicable process that was not labor intensive. As long as the professor likes you, you'll do fine all in all. Doing well in the class previously helps of course.
I applied through college or university. I interviewed at Lehigh University (Bethlehem, PA) in Aug 2016
Interview
I was enrolled as a graduate student in the Department of Mathematics and I was designated as a grader in the first year. Since my grade was good and I had a good work on my grader position, I was able to be designated as a teaching assistant in my second year.
