Given below is a crossword puzzle based on this lesson. Read the clues across and clues downwards and fill up the blank squares.

Across:

1. Quantity of matter
2. Solid changes directly into vapour
3. Gas changes into liquid

Down:

4. Occupies space and has mass
5. Liquid is heated to change into vapour
6. Solid changes into liquid.

Across:

1. Mass
2. Sublimation
3. Condensation

Down:

4. Matter
5. Boiling
6. Melting