Differentiation Strategic grouping with strong speakers Build models for students to copy Modifications Extending the Learning Plants do not give off CO2 at night only! Plants perform cellular respiration 24 hours a day. Encourage students to think about why we observed plants giving off CO2 at night only, but we were unable to detect their CO2 during the day. Have students compare the chemical reaction for combustion and the chemical reaction for cellular respiration. Ask: What do you notice about these two reactions? What do they have in common?