Video of the lecture.

I started with some examples of calculating integrals of constant 2-forms over oriented planar triangles in 3-dimensional space.

I then started to give the definition of the integral of a (not necessarily constant) 2-form over an oriented surface in 3-dimensional space. I forgot to plug the power into my laptop, and so everything crashed half way through this definition. I'll give the definition in the next lecture, starting from the start and with the power cable plugged in.