RMT Basics, page 3

You Used Leverage

When you broke the pencil, you unconsciously took advantage of this weakness in tension by using leverage.

You used the mechanical advantage of LEVERAGE to focus your might at a single point ("T") on the pencil.

Engineer's hand pressing on eraser
end of pencil

What you didn't consider was standing the pencil on end and trying to crush it. You might have driven it through your hand before it yielded and collapsed.

Why didn't you consider crushing the pencil?

Because: We all know that most materials are much stronger in compression than in tension; and...

Pencils with fulcrums Engineer's hand pressing on eraser end of pencil

...we know that we can be aided by leverage, depending on how we position a thing relative to the direction of the pressure (or force) we apply to it.