Video of the lecture.

Defined what we mean by the integral of a differential 2-form over an arbitrary oriented surface S.

To re-inforce our understanding of this definition a couple of integrals were evaluated.

It is worth repeating: differential 2-forms can be regarded as symbols which obey certain algebraic rules (such as dx ∧ dy = -dy ∧ dx) and which can be integrated. We have a full and precise understanding of what the integral of a 2-form represents, and we'll not worry too much about what a 2-form itself represents. The algebraic rules for 2-forms are derived from properties that clearly hold for their integrals