In case this is of interest....
I would like to share my lectures on Microeconomics that I have posted on
YouTube. In these lectures, I have used graphs to explain simple Economic models. One advantage of this approach is that it also works in solving optimization problems when the objective function does not satisfy desirable properties such as concavity and differentiability. For example, these are my lectures on the topic:
Public Goods Here I've used the Dolbear triangle to represent the general equilibrium model of a simple public good economy in a graph. I've also shown how to find the Pareto efficient allocations and solved a couple of problems using quasi-linear and linear utility functions to demonstrate how we can use the triangle to find efficient allocations. (Just like the way we use Edgeworth Box for the private goods case). Graphical approach helps us to find efficiency at the corner points and also works in situations when utilities are not-differentiable or even discontinuous.
These lectures/tutorials can be useful for undergraduate Economics students who want to learn how to approach and solve problems.