Differentiation Modifications Less experienced students may benefit from experiences helping them to see that air is really a form of matter that has weight and occupies space. Tips The Three Facts about Atoms are important. Make sure students understand them and can apply them to the gases in air. Extending the Learning Have students mass an empty balloon and a balloon filled with air (or conduct this as an investigation). This will allow students to see that air is matter and has mass. Students can explore other materials in air, including common gases such as argon, particles such as dust or smoke, or polluting gases such as methane or nitrous oxide. Have students experiment with the molecular model kits before the quiz in Activity 2.4. Have them construct simple molecules that they will use throughout the Unit: H2O, O2, CO2, and ethanol.