A grain of salt.
A grain of sand.
Word: "grain"
the same meaning

This school is well-known for having teachers of high quality.
The quality of students has risen.
Word: "quality"
the same meaning

We looked through the glass to see stars.
Would you like a glass of milk?
Word: "glass"
different meanings

Don't fire until you see the whites of their eyes.
Oil fires the furnace.
Word: "fire"

different meanings