Earth and Space     Changing Materials

Pupil Activity

When you walk outside in the winter time you probably have seen your breath coming out like steam. This shows us that the air we breathe out contains more water vapour than the air we breathe in. This water vapour comes from the lining of the respiratory system.

Materials:

paper towel, hand mirror

Method:

• Use the paper towel to clean and dry the mirror.

• Hold the mirror near, but not touching, your mouth.

• Exhale (breathe out) onto the mirror two or three times.

• Examine the surface of the mirror.

Questions:

What happens to the mirror?

Why does the mirror become fogged?