It is much easier to slice a piece of pie with the edge of a sharp knife than with the edge of a pencil. Explain this in terms of applied pressure. Just Putting this out there for other students

The Knife will have more pressure than the edge of a pencil because it has less area. The pencil will have less pressure than the knife because it has more area.

Note: As pressure increases the area will decrease and as the area increases the pressure will decrease.