Organic Chemistry in 8th Grade
As a Waldorf homeschooling teacher, I have finally reached that milestone of completing my last 8th grade main lesson. My youngest daughter will still continue to homeschool for high school, but I definitely have that feeling that I have ended an era. This is my fifth child and I have been homeschooling grades K-8 for the last 25 years!
Those of you who are doing upper grades work with your homeschooler might appreciate how I handled this final three week OrganicChemistry block. Below are some of the highlights.
This three week unit explored organic chemistry in relation to nutrition with labs on carbohydrates (sugars, starches), fats and proteins.
The primary reference books I used were Eric Fairman’s A Path of Discovery, Grade 8; Wonders of Waldorf Chemistry by David Mitchell, What Einstein Told His Cook by Robert L. Wolke and Donna’s booklet, From Nature Stories to Natural Science.
In Week One, I focused on an overview of chemistry terms and definitions, a review of the element carbon, and a close look at plant photosynthesis. The question I posed at the beginning of class was whether or not all food is really packaged sunlight. We looked carefully at how the plant is able to produce carbohydrates due to its ability to absorb carbon dioxide in the air which aids in the assimilation of light in the process of photosynthesis. The products of photosynthesis are oxygen, released for both human and animal life, and glucose. We studied how photosynthesis occurs only in the presence of light using chlorophyll in the plant’s leaves to absorb the light from the sun and give the plant power to transform absorbed carbon dioxide into other carbon compounds and oxygen. We looked at cross section drawings of a leaf and studied its layers . We looked at the role of water as a raw material in photosynthesis and how water is drawn up the plant. The light and chlorophyll essentially decompose the water, and the oxygen held in the water is released through the stomata into the atmosphere.
So how does all that become sugar and starches? We looked at how the leftover hydrogen from the water reacts to form 3-phophoglyceric acid which in turn reacts with three parts of the carbon to become a simple sugar, glucose. The first product of photosynthesis is sugar, but as the light diminishes, the sugar is transformed to starch. The starch further transforms into the complex carbohydrate cellulose, which the plant uses to build its plant structure. The carbohydrates produced by the plant are in turn used by the human and animal world. The end products of mineralized cellulose become coal, natural gas, oil and peat.
What about protein formation in the plant? We studied how carbon, oxygen and hydrogen combine with nitrates and mineral nutrients from the soil to manufacture proteins in the plant. Animals and humans ingest plant carbohydrates and proteins and excrete manure, which complete this amazing cycle by providing the mineral salts for the earth. Humans and animals break down the nutrient compounds through digestion, consume the oxygen and give off carbon dioxide as a byproduct, continuing the respiration cycle so necessary to plant photosynthesis. This entire process always evokes in me a sense of reverence for all life and amazement at the unity of life.
The homework for that first week was to study the definitions for a vocabulary test the next week; do a writing assignment on the naturally occurring allotropes of carbon; write a short report on the history of sugar; and diagram/ draw in color the process of plant photosynthesis showing (1)how light captured by the plant is released as oils/fragrance and nectar in the flower; (2) how plant respiration creates oxygen; (3) how the plant manufactures sugar, starches and proteins.
In Week Two, we began by doing our first labs on sugar. We did experiments with melting sugar, an experiment on the solubility of sugar types, and one on the chemical relationship between sugar and water. All her labs were written up. She also was assigned the chapter, “Sweet Talk” from the What Einstein Told His Cook with 23 short answer questions that I prepared for her to fill in based on her reading. Her cooking assignment was to make the Devil’s Food Cupcakes from the book.
Our next lab experiments were with starches. We observed the solubility of starch in cold water, the boiling of starch, the burning of starch and an indicator test (using iodine) for starch.
Our next lab experiments were with fats. We did experiments on the solubility of oil, (and compared that with our earlier experiments with sugar and starch), the heating of oil ( including a very dramatic flash point with canola oil !), and an experiment on the reaction between oil and soap.
She was also assigned the chapter on “The Fat of the Land” and had 40 questions to answer from the chapter.
In Week Three we finished our unit with Proteins. This week we did lab experiments using a biuret reagent to test for the presence of proteins, did several experiments using eggs to demonstrate the solubility and heating of proteins (again comparing these to our earlier experiments with starch, sugar and fat), looked at the composition of butter and its reaction with a liquid detergent, and ended with some experiments with heated milk. We finally boiled milk down to show the presence of the milk sugar lactose. We also had a lot of fun making mozzarella cheese from a cheese making kit .
She did short answers to 45 questions I prepared from the chapter on proteins, “Turf and Surf” and she studied for a final exam I created that was 29 questions long (plus an extra credit question) that covered the most important areas we studied over the last three weeks.
She and I both really enjoyed this final main lesson and even though no one really likes to take exams, she was fine about the final exam since she knew that it was part of her preparation for high school level work. I highly recommend using the Einstein book because the author makes the chemistry of food both fun and tasty.
Blessings on your homeschooling journey!