Begin by asking students how they would break the stick? Most, if not all, students will break the popsicle stick in weak-axis, three-point bending. Note that students have an understanding of stresses without even realizing it!

Let’s do the math! Why is this the best configuration for failure?

Assume the normal stress limit of the wood material is 8000 psi. Calculate the load required to break the popsicle stick in tension, strong-axis bending, and weak-axis bending.

The calculations for this demo are attached in the images. These calculations also show the relationship of internal forces and internal stresses for flexural elements.