STEM Challenge
Summary
As we complete the explorations in denaturing, distillation, saponification and polymerization, we should reflect about the significance of our work as it relates to science concepts, chemical engineering practices, and the model for life and work of George Washington Carver.
• We have learned how to use common things to build a classroom laboratory. Although we all like to use sophisticated materials as scientists, it is important to see how “necessity is really the mother and father of invention” and that elegant ideas can very often come from humble beginnings. The core science we know is a result of millennia of intelligent and observant people using simple materials in unusual ways. The legacy of Carver and his need to use materials that were available give us an opportunity to both appreciate what access we do have to sophisticated materials and to carefully consider the reuse and recycling of materials we discard from our daily life. Most importantly it demonstrates how all scientists must invent as they discover.
• We have learned about certain chemical and physical processes. Chemically, we removed protein from milk using a process of denaturing. By adding borax we made a polymer. We also made a strong chemical, sodium hydroxide (lye), by soaking wood ashes. By adding this chemical to a liquid fat we made soap by saponification. We found in the exploration of distillation, yeast facilitated a chemical change by fermenting sugar into alcohols and carbon dioxide.
• Mechanically or physically, we separated different liquids from a mash through distillation and also filtered out particles. We extracted sugar from sugar beets by dissolving the sugar in water as a suspension. We removed starch from potatoes in a similar way. The starch was added to lint or newsprint to make recycled paper.
• We learned the specific concepts and vocabulary as we learned processes:
Distillation:Purifying a mixture by boiling and condensing a liquid.
Evaporation: Removing the water or “solute” from the solid.
Fermentation: Using microorganisms to digest sugars to make alcohol and carbon dioxide
Saponification: Adding Lye (sodium hydroxide) to fat to make soap.
Filtration: Removing the solid portions of a mixture using paper.
Hydration: Using water to dissolve materials and make solutions or suspensions.
• We learned the names of chemical combinations and their characteristics:
Mixture: A combination of material that can be separated by ordinary means (distillation, filtration, evaporation, etc.) Salt and sugar, sand and water are examples.
Compound: A combination of chemicals that cannot be separated by ordinary means. Soap, alcohol, sugar, salt are all compounds. No matter how much we try to take them apart with ordinary means, they will not separate.
Chemical Change: Atoms and moelcules are in new permanent arrangements.
Physical Change: A change of state, atoms and molecules remain the same.
Solution: A mixture of water or other solute such as alcohol where a solid or liquid chemical becomes invisible. Salt in water and alcohol in oil are examples of solutions. Solutions may have color, but they are always transparent.
Colloid: A mixture of water and chemical where the solid chemical is still visible. Milk and mayonnaise are examples of colloids. Colloids are mixtures that can easily change to suspensions when certain conditions are met.
Suspensions: A mixture of water and any other material that is very temporary. With time the chemical will settle to the bottom (or top). Water and dirt (muddy water), oil and vinegar are examples of suspensions.
Solute: The liquid part of the solution.
• We also learned how to make certain laboratory equipment:
A heating stand
A graduated cylinder
A filtration paper and funnel
A distillery
A laboratory process
• We learned to think like chemical engineers.
We learned the science content that was necessary to search out new solutions to problems. We needed to understand how chemical processes work before we can apply them to new circumstances.
We learned how an engineer gathers information about the need of society and then works to find a solution that is beneficial for all concerned.
We learned how to develop a systematic way of testing our new solution by developing trials, by collecting data, and by redesign to optimize the product.
We learned how to communicate our findings and recommendations based on how the new application or product would serve the needs of society.
We learned to use a notebook to record all our work, just as engineers would record their work.
What we have accomplished in this unit thus far is to join our experience with that of Carver--perhaps just a bit. We know some of his personal story, we know some of his scientific work, and now we know some of the knowledge he had and some of the skills he possessed as he began his work at Tuskegee. We now are ready to return to the story and ask the real question--what is it like to be a scientist/engineer?
Solving Problems like Carver
In this final part of the unit, students are invited to explore their own questions by using peanuts (or pecans), sweet potatoes, or peanut butter.
"One reason I never patent my products is that if I did it would take so much time, I would get nothing else done. But mainly I don't want my discoveries to benefit specific favored persons." George Washington Carver
Inventing Applications for Agricultural Products
In this exploration we will give students peanuts or sweet potatoes and ask them to use the processes they have learned to find a possible new use. Determine peanut/nut tolerances before engaging in this exploration. If nuts are a serious allergic issue, select other food products such as soybeans, avocados, or other fruit or vegetable that has oil/fat content, fiber, and sugars.
Materials
• Several days in advance, prepare sweet potato by slicing very thin and air dry it until brittle. (Prepare this several days ahead of when it is needed.)
• Several days in advance, if using peanuts, separate the peanut oil from the peanut protein and fiber from a jar of nonhomogenized peanut butter. Spread half the resulting protein/fiber mixture and air dry on foil. Keep the oil in a separate container.
1) Read another episode in Carver's history telling of Carver's concerns with the farming of peanuts and sweet potatoes and the farmers' response to his advice.
2) Consider the problems associated with having a large crop of peanuts without a market for them! What would Carver do now that the farmers are in need of selling their crop?
3) Encourage the students to reflect on this section of the story and to use their prior knowledge to explore possibilities for peanuts and sweet potatoes. How can we be like Carver and find some uses for these materials? Have students capture their response to the story and their ideas in their STEM Notebooks.
Some of the possibilities may be:
Peanuts. (Use unsalted, unroasted peanuts or peanut butter. Peanut butter is actually best because the peanuts are already pulverized. Check ingredients to be sure the only ingredient in the peanut butter is peanuts and salt is okay.)
• As a food, peanut oil can be used as any other oil to fry, bake or combine with vinegar as a salad dressing.
• With lye, it could possibly be made into soap.
• The peanut material without oil has protein. Perhaps it can be mixed with borax to make glue or plastic.
• Is there fiber in peanut? Perhaps it can be made into paper by adding starch.
Sweet potatoes
• Is there sugar available? Can these vegetables be a source of starch? Can they be fermented?
• Are there fibers in sweet potatoes that can be made into paper?
4) The challenge to students is at this point to use either peanuts or sweet potatoes (or other fruit or vegetable) and find some utility other than the basic use (food). Using their newly found skills, laboratory equipment and knowledge, they then can approach these food stuffs as Carver did.
5) Students should work in pairs for this exploration and carefully plan what they intend to do based on the science they know. It is important to not engage in a free-for-all at this point. Students need planning and foresight about what they decide to do before they start mixing things. They should record their plans in the Engineering Notebook and get approval before proceeding. Have each pair prepare a process sheet for experimentation as well as accommodation for how they will collect data and where they will record observations.
6) Review classroom safety rules and proper behaviors with open flames, chemicals and glassware. Give students ample time to conduct explorations when they have your approval to commence.
Facilitating the study
7) It may be helpful to have a parent or assistant in the classroom during this portion of the unit. Students may need help with laboratory equipment or may need additional chemicals or consumable materials to conduct their experiments.
8) Determine the time allotted each day for explorations and arrange a specific area in the classroom where students may store their experiments. Encourage proper disposal of consumable materials and safe storage of equipment and chemicals.
9) During explorations students may find new routes or ideas. Encourage this, but require that pairs revisit their plans and rewrite their proposed experiments.
10) After students have made several attempts at solving their problems, close the inquiry time and have students consider their materials and results by reviewing their notebooks.
11) Set all equipment aside and have students next think about how they will communicate their findings. If they have discovered an appropriate use or have a possibility for peanuts or sweet potatoes, then they need to be able to communicate that to peers and to interested members of the community. Invite parents, school personnel or local scientists to the “demonstration” of discovered products. Explain to students that they will be responsible for either a “poster session” or “chalk talk” where they will display the process they used and discuss the product and its potential application.
Assessment
A communication rubric can be provided to establish appropriate visual, written and oral communications requirements.
Posters and Chalk Talks should display the process used, a sample of the product, and the anticipated applications of the product. Accuracy of information such as use of correct scientific terms, accurate spelling, and appropriate description of processes can be assessed in the area of scientific literacy. Appropriate use of language, visually appealing presentations, and oral fluency can be used to assess language arts goals.
Closing the Unit
Students should be invited to return to the Carver story at the end of their exploration. Have students review their work in light of the hundreds of discoveries and applications found by Carver. What kind of scientist and person was this man? What kind of scientist, inventor, discoverer will you be?
