GRADE 7- BIOLOGY

To verify that human beings give out carbon dioxide during respiration:

Breathing involves exchange of two gases – oxygen and carbon dioxide. Oxygen is inhaled and carbon dioxide along with water vapour is exhaled out. Lime water turns milky white in the presence of carbon dioxide

Students of grade seven were given test tubes filled with freshly prepared lime water and a straw. They were asked to blow air into the test tube using a straw. The limewater initially was colourless and finally when air was blown into it, it turned milky. This confirmed that human beings exhale carbon dioxide.

The students enjoyed it thorougly