Challenge 1: A Stack of Blocks Toppling Realistically When Knocked — Solution Walkthrough

The answer:

Per this chapter's own material, marking each block as a Rigid Body
achieves this directly. Rigid Body physics treats each object as a
solid, non-deforming object that collides realistically with other
Rigid Bodies — falling under gravity, bouncing off surfaces, knocking
into and displacing other objects, all calculated automatically once
the simulation runs.

Why hand-keyframing would be impractical here:

Per this chapter's own material, a stack of blocks toppling involves
so many interacting variables — each block's own reaction to being
struck, its subsequent collisions with neighboring blocks, how those
collisions cascade further — that manually keyframing a convincing
result would be extraordinarily tedious, if not practically
impossible.

Why Rigid Body simulation solves this specific problem:

Rigid Body simulation calculates exactly this kind of complex,
interacting motion automatically, based on real physical properties
like mass, friction, and bounciness, rather than requiring every
individual block's own motion to be manually placed as keyframes.

WHY THIS WORKS AS AN ANSWER
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This exercise checks that a multi-object collision scenario is
correctly matched to Rigid Body simulation, with the impracticality of
hand-keyframing correctly understood as the reason simulation is the
better approach here.