Vox Humana wrote:
> "Jude" > wrote in message
> oups.com...
> > Well, today's the big day. My 9 year ld daughter will be baking
> > quick-bread all day long for the science fair. We have a recipe for a
> > good oatmeal-raiain bread. Her hypothesis is that a combination of
> > baking soda and baking powder will produce the highest rise. Our other
> > loaves will contain: no leavening; just soda; just powder; and dry
> > yeast (not proofed, just dumped in). She's going to measure the height
> > of each loaf and also have 3 testers (herself, me, and my BF) taste and
> > rate the on a scale of 1 to 10 for lightness or density, chewiness or
> > softness and a few other characterisitics. Should be an interesting
> > project!
> >
> > Through her preliminary research, she has learned about how leavning
> > agents produce carbon dioxide bubbles which cause the loaf to rise.
>
> Since she has already researched how CO2 is produced, it seems that the
> basic design of the experiment is flawed. First of all, the inclusion of
> yeast is inconsistent for two reasons. First, it is not a chemical
> leavening agent. Secondly, it is not used properly as compared to the
> chemical leavening agents since you are not allowing any time for CO2 to be
> produced by the yeast. In other words, you have all too many variables to
> the experiment and any findings will be inconclusive. If she were older, I
> would suggest finding some additional chemical leavening agents to compare,
> but this would add too much complexity.


Ummm, the child is 9. I thought it was pretty good that she was able to
identify that yeast is another ingredient used to leaven breads. The
only variable is that she is changing the leavening agent. She will
subsititute 2 t of yeast for the 1 t each of soda and powder in the
original recipe. She will see why it doesn't work, and she will learn
that yeast leavens differently that soda or powder. There really is no
other variable in effect here. Her science teachers agreed that this
was an entirely appropriate experiment for a 4th grade. This is not a
college-level organic chem class. Its the elementary school sciecne
fair, and a kid whose mom cooks and bakes, thus a fun project to try,
emulating Mom.
>
> The second issue relates to your (her) assumption that the combination of
> baking soda and baking power will have the best results. Unless there are
> acidic ingredients, the baking soda will just sit there and produce no
> additional CO2. This indicates that neither of you really understand how
> CO2 is produced by chemical leavening agents.

Again, this is a fourth grade. It is not MY assumption, it is HER
hypothesis. A hypothesis for a science fair project is simply a theory
to be tested. How many fourth graders have a deep knowledge of how CO2
is produced by chemical leavening agents? My knowedge has zip, zilc,
zero to do with this. Amazingly enough, I'm a mom who is actually
making HER do her own science fair project and see what she can learn.
My knowledge does not come into play here. The purpose of the science
fair is for a child to deisgn an experiment and then to perform it.
They analyze the results and gain new knowledge based on what happens.
The purpose of her experiment os so she CAN learn more about how
leavening agents work. Not to mention that since the original recipe
calls for a combo or soda and powder, it's probably a good hypothesis.
>
> A more easy to understand and therefore more educational comparison would be
> to make the recipe with no leavening agent, with baking soda only, and with
> baking powder only. The first to batches should be the same - flat. This
> would show that baking soda ALONE is not a leavening agent. The batch with
> baking power should be normal, thus proving you need both an acid and baking
> soda (aka BAKING POWDER) for CO2 production. An extension to the experiment
> would be to use increasing quantities of baking powder and use some
> objective measure like density to measure the optimum amount of baking power
> per unit of batter. There is a point where too much leavening agent will
> cause the product to collapse and become more dense, not less.

I disagree that it would be more educational to bake only variations on
the bread and never follow the original recipe we are using. What would
she learn from that? The purpose of comaprison is to have 1 loaf that
comes out exactly as it sould, following the recipe to a T, and then
vary the recipe to see what happens. Without 1 loaf made exactly as
directed, we have no 'control' to compare to.

You do realize that most 4th grade science fair experiments consist of
putting food coloring into a vase with a carnatin and seeing the flower
absorb the color? This one she came up with is perfectly appropriate
for a little kid. perhaps a high school students with many more years
of sceintific experimentation would be interested in the advanced ideas
you propose, but not a little kid.