Before setting off as an entrepreneur I was a Lecturer at UC Berkeley. Here are some videos of me teaching:
Working through some problems about convergence of series. (Section 11.7 of Stewart Calculus.) If you're a student this might be helpful for approaching problem solving, persevering past getting stuck, and writing clear solutions.
In a previous life I did mathematics research is in 3-dimensional topology and geometry. You can see all my papers on the arXiv.
I previously held positions at UC Davis, the University of Sydney and the University of Oxford. Before that I completed my PhD at Oxford under the outstanding guidance of Marc Lackenby. Before that, I completed a Postgraduate Certificate of Education, also at Oxford.
Here is an email I wrote to my students in the Fall of 2013 that went viral, and was read by more than 1 million people.