Activities and Strategies
High school students are familiar with some natural polymers such as DNA, proteins, and starch, or at least they will be after they have finished biology. They will have some exposure to the general definition of a polymer: a molecule of repeating subunits. For this unit the objectives are as follows: The students will understand the basic structure of polymers, the unique properties of plastics, how plastics are manufactured, what happens to plastics as they enter the waste stream, which plastics can be recycled and the effect plastics are have on the oceans.
Investigations
Lesson one: Making GAK is a lab activity whereby students can make a synthetic polymer and have tactile experience with its mobile flexibility. Students make this synthetic polymer by adding a saturated borax solution to white glue and water solution to trigger cross linkage. They then observe, explore, and record observational data on the behavior of the polymer. Cross-linkage is discussed.
Add: 1/2 cup (or 125ml) water to 1/2 cup (or 125ml) Elmers glue. Mix. Add 3 drops of food coloring (optional). Make a borax solution by adding 2 heaping tablespoons borax (You can buy this at a grocery store or online) to 1 cup of water (or 250ml) and stir vigorously. Add 1/2 cup or 125 ml of Borax solution to the water and glue mixture. Stir. Store in a plastic bag. Students then observe, explore, and record observational data. Resource Area for Teaching has an Idea sheet with the instructions for making Gak. 2 1
- 10-15 minutes Intro and lab instructions
- 15-20 minutes Students mix materials, observe and record
- 10 minutes discussion, analysis and conclusions
Lesson two: Absorption of Water by Polymers: Some polymers are super absorbers. I plan to do a demonstration of this by adding water to a small amount of Instant Snow Polymer that can absorb water many times its weight in water. Sodium acrylate is the superabsorbent polymer used in diapers. A cross-linked polymer in gel form, it can absorb more than 500 times its weight in pure water. Students can try different liquids to see if absorption is affected. Classroom sodium acrylate can be purchased at Resource Area for Teaching in San Jose, California or through the Flinn Scientific catalogue.
Lesson three: Students will be exposed to the chemistry and early history of a man made polymer. I will make nylon by floating hexanedioxyl dichloride over diaminohexane. Where they interface is where nylon is formed and then it can be spooled out to show the class. The two chemicals must be in a 2:5 ratio. Pour the hexanedioxyl dichloride into a glass beaker. Slowly pour the diaminohexane over the layer of the hexanedioxyl dichloride. Prevent mixing. Let this solution sit undisturbed. You will be able to see two layers. Notice a small layer forming where two chemicals interface. With your tweezers, pinch and pull up a small amount of the substance. It will come out in a thread. Pull up the single thread to eye level and place the end of the thread of nylon onto a spool. As you slowly turn the spool, the nylon will thread out of the solution in a long, thin string. Continue winding the spool. A kit can be purchased from Flinn Scientific. 2 2
Lesson four: Shrink Math, as it is called at Resource Area for Teaching, is a fun activity where students measure and record the area of a rectangle of #6 plastic. It is then baked in a toaster oven, designated for science activities, at 250 degrees for a minute or so. This procedure involves students using heat to distress the polymer to return it to it original state. Students will re-measure area and density. Manufacturing is discussed.
- 10-15 minutes Intro and lab instructions, perform introduction
- 15-20 minutes Students draw, measure, heat, observe and record
- 10-15 minutes analysis and conclusions discussion
Lesson five: Jigsaw research: Students research and present a topic of interest to them such as alternatives for fossil fuel based plastic/bioplastics, plastic in the oceans/gyres, animals digesting plastic, recycling, density of plastics, recycling numbers, nurdles in the environment, plastics in agriculture etc. They must include at least five facts, a visual and a prop or realia relating to the topic.
- Day one: introduction of topics, review of expectations
- Day two: computer research on topic
- Day three and four: presentations
Lesson six: The unit will culminate in an up-cycling project to be displayed at Maker's Faire in the spring: Students design and make an item using common plastic materials. This is a creative, critical thinking and problem solving activity that is done over several weeks. They must build a prototype with instructions to share with the public.
- Day one and two: research plastic upcycle projects
- Day two: computer research on topic, students choose or design a project
- Day three and four: gather materials for project
- Day five and six: build project
- Day seven: students write share sheet that goes with project
- Day eight and nine: student share project with classmates
Lesson seven: Plastic Quilt: This activity is meant to be an aid to visual awareness of how much plastics we use on a daily basis. Students collect plastics they have come into contact with over a unit of time i.e. one week, make decorative quilt panels from the plastic collected, these are attached and displayed. Panels can be approximately 8 by 11 inches. The foundation panel might be a large plastic wrapper i.e. chip or frozen vegetables, and then students can attach other items with double stick tape or thread.
Lesson eight: Environmental Lunch is a one-week activity done outside of class. Students make a chart to record the food they consume at lunch. Emphasis is on the packaging. All packaging is recorded and sorted by type, recycle ability, reusability etc. The data are then analyzed. Students record all packaging items including plastic items from their lunch to evaluate habits and suggest ways to limit plastic waste.
Lesson nine: I will do a lab to make a bioplastic out of cornstarch, potato starch or milk. The milk-based bioplastic involves adding vinegar (2tsp) to milk (2 cups) over heat. casein is formed. The liquid can be drained off and then the polymer left can be formed like clay.
§ Day one: computer research on bio plastics topic
§ Day two: 10-15 minutes Intro and instructions
§ 15-20 minutes Students measure, heat, observe and record
§ 10 minutes discussion, analysis and conclusions
I base my lessons on the constructionist approach. Constructivism is a style of teaching and learning based on the premise that knowledge cannot be simply given by direct instruction by the teacher at the front of the room to students in their desks. Rather, students learn through active hands on approach that stimulates the mental process to construct knowledge. Students are the builders and creators of meaning and knowledge.
The labs: Making bioplastic from Starch and the demonstration of Making Nylon are appropriate for high school science lab settings, and some middle school settings as well. This must be based on judgment of the teacher. If a teacher is not comfortable doing a certain activity for safety reasons, then do not do it.
The Investigation activities: Exploring Absorbency of Polymers with diaper material, Shrink Math and Making a Polymer (GAK) may be done with students 5 th grade and up at the teacher's discretion.
Data collection assignment: Environmental lunch requires the student to record the plastic used at lunch everyday for a week. The students are asked to graph, analyze and extrapolate the data. This is appropriate for upper elementary and above.
Craft Project: Students make an artistic visual collection of plastic food packaging like a quilt to hang on the wall. This might represent a unit of time for which the plastic was collected, i.e. one week. This is appropriate for upper elementary and above. Both the environmental lunch activity and this craft project can be done in the beginning, middle or end or the unit.
Projects: The Maker's faire Up-cycle project can be applied to any secondary grade level to encourage problem solving, designing and critical thinking. Jigsaw research projects (on the recycling numbers or other areas of interest as noted above) are when a student or small group has a specific topic to research. They then do a presentation to share that information with the other students. Students must be mature enough. Teacher use your judgment weather this is appropriate for your students. This is probably appropriate for upper elementary and above.
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