The sun brings life

 Fill a large glass jar with fresh water and place in it several shoots of water weed.

Place the jar in sunlight, and at once small gas bubbles will rise in the water. Invert a funnel over the plants and over it a water-filled glass tube. The gas, which is given off by the plants slowly, fills the tube.

Plants use sunlight.With its help, in the presence of chlorophyll, they make their building material, starch, from water and carbon dioxide, and give off oxygen. Oxygen has actually collected in the glass tube. If you remove the tube and hold a glowing splint in it, the splint will burn brightly.