This was a continuation of the Tuesday Science class. One of her kids was allergic to our birds, so we had to have class outside (and we had to stop when the weather got cold!). What could we study outside???
I dunno, what's outside to study? (Look out the window.) Trees!
- We walked around the neighborhood, learning to identify trees by their leaves, bark, structure and leaf scars.
- We looked at slices of wood and learned about the heartwood (the dead but supportive center) and the cambium, the thin ring beneath the bark that is the living tree. The ring regenerates each year- last year's cambium will be heartwood this year (or possibly sapwood, an intermediate stage)- and this is why we can tell the age of the tree by counting its rings. This is also why cutting a ring around a tree will kill it.
- We talked about the xylem and phloem (both are in the cambium) and went through the progress of a drop of water from the root hairs in the soil up through the xylem and out of the leaves on the top of the tree, and the progress of sugars down from those leaves through the phloem to the roots.(If you ever get confused, phloem flows down).
- We used magnifying glasses to look at the stoma on the leaves. These tiny holes are the trees lungs. Fascinating stuff!!
- This was in early November, so we also collected colorful leaves and talked about the fact that these colors were always there, just covered up by the large quantity of chlorophyll needed for photosynthesis.
- We reviewed the seasons, and the angle of the Earth causing the shortening of the days that signaled the trees to stop making chlorophyll.
- We talked about roots. Roots absorb water, store food and anchor the tree. But did you know that roots only go down two feet or so? It's true! The roots go out nearly three times the length of the branches, but they don't go down (comparatively) very far at all. This is because, below a certain depth, there isn't enough oxygen in the soil for the roots to survive.
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