See How Plants Breathe 
Fill a glass jar with water. Select a large leaf from a plant or tree nearby, drop it into the jar and screw the lid on. Place the jar in a sunny spot. After an hour, ask students to look in the jar and report what they see inside.
What Do You See?
What would happen if we held our breath, underwater, at the pool and then let out air?
Bubbles!
As oxygen is released by the leaf in the sun, many tiny bubbles form showing photosynthesis in action. The process of photosynthesis is what allows us to see the bubbles — as the leaf releases its extra oxygen while submerged, the oxygen can be seen as bubbles in the water. As a leaf creates that energy, it needs to get rid of the items it no longer needs so it will expel both the extra oxygen during photosynthesis along with water, called transpiration.
And since oxygen is lighter than water, the bubbles will eventually rise to the surface.
Are We the Same?
Does a tree or plant breathe the same as we (humans) do? No. A plant, tree or leaf doesn’t have any lungs or respiratory system; but it is a living organism just like we are.