What to do:
1. Carefully cut the top and bottom of each stem with scissors.
2. Take a close look at the cut ends of each stem with a magnifying glass. How do these cross sections compare?
3. Gently rinse one end of each stem with water to clean off any dirt.
4. Put the unrinsed end of the stem into the glass of water and put the cleaned end in your mouth.
BLOW! Do you see bubbles in the water? 
Try this with the other stem too.
What is HAPPENING?
When you looked at the stem cross sections, you probably noticed that the aquatic plant stem had large air spaces and the land plant stem had very few air spaces. Most aquatic plant stems are made of spongy tissue full of holes. This makes it easy for air to travel from their leaves above the water, through the holes in their stem, down to their waterlogged roots. Aquatic plant stems also need air spaces to make them light and buoyant or their weight would drag their leaves under water. The land plant stems have smaller air spaces because they need stiff stems to support their leaves in the air.
