Need to prepare: salt, clear water, beaker, glass rod, Petri dish.

1. First, pour a proper amount of water into a beaker, as shown in the figure.

2. Then add salt into the beaker continuously.

3. Then stir with a glass rod until the salt can no longer be dissolved in the beaker, and a saturated solution is prepared.

4. Pour the saturated saline in the beaker into a glass Petri dish.

5. Then put the Petri dish on the balcony and keep it for more than ten days.

6. At last, salt crystals will appear, as shown in the figure below.