First, students will learn why the greater side subtends the greater angle, in any triangle. For a proof, read this or watch this. Next, students will learn why the converse is true. That is, the greater angle subtends the greater side. For a proof, read this. Then students will practice ordering the sides and angles of a triangle, when only some are given (video).
Conclude by giving your students these challenges:
Find the area of the green square:
Here's the solution.