From High School Arithmetic to Group Cohomology
course notes
Mathcamp
algebra
Group extensions and exact sequences, arrived at by taking carrying in multi-digit addition seriously.
\[ 0 \longrightarrow \mathbb{Z}/10 \longrightarrow \mathbb{Z}/100 \longrightarrow \mathbb{Z}/10 \longrightarrow 0 \]
A week-long class from Mathcamp 2019 based on a fun paper by Dan Isaksen titled A cohomological viewpoint on elementary school arithmetic. It introduces group extensions and exact sequences as a way to interpret the addition of multi-digit numbers.
It is designed in an IBL format. The prerequisites are group theory.