Need help teaching 2nd graders
brateaver at aol.com
brateaver at aol.com
Thu Jan 16 05:16:00 EST 1997
**You can easily demonstrate root hairs. Set an onion in the top of a
glass jar, and add enough water to immerse the base of the onion--where
roots grow out. Long, white, very delicate root hairs will grow out from
the roots that develop. It is important for the children to see that these
are really single cells. Can you not get a slide projector and show slides
that show such things?
**You can make a homemade rhizotron type of exhibit, if you set a
growing plant in a glass jar, making sure that the root is appressed
against the glass, so the children can see the root growth. If you could
get an old battery jar, that would be good to use.
**The very best root exhibit is that of nitrogen-fixing in bean/pea.
You should explain that there are some roots that can take nitrogen
out of the air, where nitrogen is 4/5 of the air, and thus enable the
plant to get the nitrogen it needs to make protein. This is done by
certain bacteria, that can enter roots and multiply there until the root
has to give them special room, which ends up making nodules you can see on
legume roots--peas, beans, sweet peas, etc.
This can so easily be done in a classroom. Get some legume seeds and
order a small package of legume bacterial inoculant from a seed company,
such as Gurney.. This is a dark brown powder which is applied to seeds
Make the seeds sticky with a dab of diluted honey, roll them around in
the powder, plant them in a glass jar, next to the glass jar surface.
Even when quite young the seedlings will show nodule development. Explain
that only when nodules are pink are they actively producing nitrogen
compounds for use of the plant.
One big advantage of this demonstration is that it shows that something
can enter a root cell even if it is a very large item, such as a
bacterium. You can get sketches and slides to show all these points, if
you have access to a projector.
If you have not taught them about atoms and molecules, you should start
now. It seems to me that this is the most important secular topic a child
can learn--all that has to do with life. It is much more important than
history or Catholic missions or anything else that does not pertain to
basic life processes and materials.
**A very important point is that roots seek out water and nutrients.
You can show how roots will do anything to get what they need. If
confronted by the need to enter a pipe of diameter smaller than their own
diameter, they can grow into that smaller pipe,making their own tissues to
fit, and then when they get out of the pipe, return to their normal
There is in Europe a huge rhizotron where one can be under a big tree
and see its roots growing.
This is important because most people don't understand it. An
example: my neighbor has trees whose roots have grown, not down
into the earth, but sidewise into my yard, which is 3 ft higher. I
showed this to some people and explained that those trees were
stealing MY water and MY fertilizer.
They did not get the point, because, even though they know my
soil is exceedingly good and kept moist, they asked: "Wouldn't
YOUR tree roots grow into the neighbor's yard?"
This was a foolish question, because the trees are desperate
for nutrients,and go seeking them, so would have to aim for my
yard, where such are available, not in their own yard, which would
keep them starved.
**You could show this difference in direction of growth, in a big jar,
by packing one side of the jar with just sand, which has no nutrients, and
the other half of the jar with very good soil, so the kids could see roots
heading for the real soil instead of the sand.
**If you could take the children on a "field trip" so they could see
this in another way, you would emphasize the point. Usually it is not hard
to find trees, often alongside a sidewalk, where the roots are visible and
maybe even cracking the sidewalk. This proves that the roots learned they
cannot get water from the street, but only from beyond the sidewalk,
inside someone's yard. They go hunting for water and grow toward that
((I have a neighbor with a corner lot, whose big tree's roots were
spread all over the lawn surface, because she skimped on water and
the roots were streaming in all directions, desperate to find a
water source. The normal direction DOWN, was denied them, so they
had to stay close to the surface where there was lawn-depth
She had to cut down the tree, as its roots were causing trouble
I invited her to my yard, across the street from hers, where I
have many big trees, and no sidewalk troubles, because I allow a
slow water drip IN THE CENTER OF MY YARD. The trees found they
could get plenty of water if they headed away from the street into
my yard and go way down where the water descended and was ample. I
have cement block walls all around, and they are not heaved up.))
**Another very important lesson would be proving that roots can absorb
whole molecules. Add to a jar of pure. sterile sand some molecular
nutrients, such as dilute sugar solution, or diluted molasses, or beet
juice, raspberry juice or juice of any fruit that has a red color, a
tiny bit of curry powder--whatever has a good color. They can see that
such molecular material is absorbed, and that it is not necessary for
materials to be in ion state to be absorbed.
There ought to be some way to show enzyme action in roots, but right
now I can't think of what it would be, except by slides.
((As an aside, may I say a few relevant points.
It is sad that people end up old and full of cancer and the
like, often because they ate wrongly, not understanding that
living tissue is made of atoms and molecules, and that
their health depends on the right state and position of
For example, the importance of enzymes, that make
reactions go, is overwhelming, but most people have no
idea what an enzyme is, how to get enzymes in food, and
they end up sick because they ate without enough
enzymes, maybe none at all, eating cooked food all their lives, not
realizing that only raw food has enzymes.
. They should have learned this basic biochemistry in the
first grades. Children, I am sure you have learned, are
very capable of learning, much, much more than someone 25 yrs
old. They can grasp basic biochemistry--molecular action--very
easily. They can undestand the periodica table, just as well as any
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