Urban Environmental Quality and Human Health: Conceiving a Sustainable Future

Strategies and Class Activities

At the end of the lessons, students will be able to identify food substances that are excellent sources of required food nutrients. They should be able to explain why biomolecules are classifed as polymers. They should be able to compare and contrast natural and artificial polymers. After doing the hands-on activities on making polymers, they should be able to explain the unique properties and characteristics of polymers. Using the plastic symbols, students should be able to identify food packaging that contains BPA and DEHP. As a culminating activity, each group should be able to report about their projects using power point presentations.

Learning Scenario

I love using a school-based scenario to introduce a unit. I believe students will become engage by the lessons and learning will become easy. Below is my learning scenario.

Dunbar High School is in great need of new uniforms for all sporting events. The President of Pop Cola Corporation announced that he would pay for everything, in fact, they are willing to donate two sets of uniform to every player, whatever event he is involved. School administrators, teachers, students, parents, and the whole community is ecstatic about the news. Afterall, everyone is waiting for developments like this. However, there is a catch. The school will have to sell all Pop Cola products in the school's vending machines and in all sporting events for the next five years. This will create a problem. The previous year, all pop cola products were ordered removed by the School System as part of healthy nutrition campaign. School officials ask for students' unified decision. As a student member of Dunbar, what will you do?

Bell Ringers and Scaffolding Activities for Review

To effectively make a connection between what my students already know and what my curriculum unit is all about, I will start with bell ringers and scaffolding activities. Bell ringers are generally questions about or related to concepts already learned while scaffoldings are prepared checklists used to reflect on what they previously studied. The main purpose of scaffolding is to keep students on track and simplify the task to make it more meaningful and achievable. Bell ringers and scaffolding will be my strategies to review topics covered. These will take the first five minutes of class. Table 1 summarizes the topics that students need to understand to prepare them for my unit.

Table 1: Scaffolding Worksheet

Indicate with a check mark how you feel about the following topics:

To enhance vocabulary development, I will use context clues. Context clues are words or phrases in a sentence which help us figure out the meaning of an unfamiliar word. We can oftentimes determine the meaning of an unknown vocabulary word by paying attention to other words in the sentence.

Video Clips:

To set the tone for the lessons, I will show two video clips, "A New Year's Resolution: Use Less Plastics"⁴⁸ and "The Great Pacific Garbage Patch".⁴⁹ These videos talk about how hundreds of million tons of trash are brought to our oceans and how marine animals were affected by this global marine catastrophe. Students will discover that these man-made disaster affect even the most distant places in this planet. The clips will give important pieces of information that will be helpful for their projects.

Inquiry Labs: (Students wear goggles and gloves)

Biomolecules Lab

The foods we eat contain important organic compounds that our bodies need as nutrients. In this lab, a series of chemical tests are used to determine which compounds are present in different foods. Indicator solutions will identify the three major biological molecules, carbohydrates, fats, and proteins. Indicators are test solutions that change color for a specific substance only.

Materials:

Test tubes, test tube rack, test tube brush, 30 well well -plates, masking tape, marker, toothpicks, 10 medicine droppers, hot plate, 250 mL beakers, distilled water, food solutions A to I (apple juice, butter, cooking oil, diet soda, egg white, flour, green beans, ham, and ice cream, test indicators (Sudan IV, Biuret, Iodine and Benedict's solutions)

Procedure:

Label the three rows of the well-plates A to I, W is water which is the control. With clean medicine droppers, add solutions to each row following the letter codes. Complete food solutions in all three rows. Add ten (10) drops of distilled water to all test solutions. Mix thoroughly with clean toothpicks. On the first row (solutions A to W), add 10 drops of Sudan IV to each well. On the second row (also with solutions Ato W), add 10 drops of Biuret. On the third row, do the same for the third row. Mix all solutions with clean toothpicks for each well. Do not use toothpicks twice. Use white paper as background to observe color changes. Record the color of each reaction.

For the last test (Benedict), fill a 250 ml beaker with 150 ml of water. Place the beaker on a hot plate and heat the water to a low boil. Use clean medicine droppers to put 10 drops of each food solution into the appropriate labelled test tube. Add 10 drops of Benedict's solution. (This solution is poisonous!) Mix the shaking the test tube. Heat the test tubes in boiling water bath for 3 minutes. Use test tube holder in taking the test tubes out of the water bath. Observe color changes using white paper as background. Use Table 2 to compare results. Write results in lab journals.

Table 2: Color changes for positive results:

After performing the lab, students will complete the following tasks:

1. Classify the foods tested in three groups based on similarities in color changes.
2. Identify the biomolecules present in all foods studied.
3. Answer analysis questions given below:
4. Some of the foods had a positive reaction to more than one indicator. What does that tell you about those foods?
5. Were there any food solution that did not react with any indicator? What does that tell you about those foods?

Polymer Lab

"Making Polymers" is the next activity. Here, students will be exposed to the properties and characteristics of polymers. They will see that increasing or decreasing one ingredient can change the polymer's properties.

Again, the class will be divided in five groups. Each group will be assigned to make a specific polymer. These are slime, super slurper and three kinds of gluep. Three kinds of gluep will be made using different combinations of glue, water, and borax. Students will share results.

Materials: 4% PVA solution, food coloring, 4% sodium borate, Elmer's glue, talcum powder, wooden sticks, sodium polyacrylate, table salt, sugar, baking soda, recipe cards

Group 1: Place 20 ml of 4% PVA solution into a cup. Add 1 drop of food coloring. Then add 20 ml of 4 % sodium borate. Mix thoroughly with wooden stick. Remove the blob and study the properties by stretching slowly and stretching it quickly.

Group 2: Mix 20 ml of water with 25 ml Elmer's glue in a cup. Add 1 tsp. of talcum powder. Mix thoroughly. Add 10 ml of saturated borax solution. Stir. Remove the blob from the cup and knead for a while to dry. Add talcum powder if there is difficulty in drying the blob. Study its characteristics.

Groups 3, 4, and 5: Prepare color-coded recipe cards shown in table 3 below:

Table 3: Color Coded Recipe for Making Gluep

Each group selects a color and prepares the polymer following the same steps described above. Relate the properties observed with the characteristics of some known plastics (like the famous plastic bag)

Preparing Nylon ⁵⁰ (Teacher Demonstration)

Note: Use fume hood, the vapors are hazardous), Disposal-Code A

Materials: 250 mL beaker, 50 ml petroleum ether, 1 ml sebacoyl chloride, stirring rod, 100 ml beaker, 1.1 gram of 1,6 hexanediamine, 10 ml 1 M NaOH, food coloring, forceps, graduated cylinder, paper towels

Procedure: In a 250 ml beaker, place 50 ml of petroleum ether. Add 1 ml of sebacoyl chloride. It is important to mix the solution. In a 100 ml beaker, mix 10 ml of 1 M NaOH in 15 ml water. Dissolve 1.1 gram of hexanediamine in the water solution. Add a drop of food coloring to help students see the water layer in the next step. Carefully pour the water solution down the side of the 250 ml beaker into the petroleum ether solution, without mixing the two. Using forceps, pick the center of one film that forms at the interface of the two liquids. Slowly pour the nylon fiber from the beakerand roll it up on a graduated cylinder that has a paper towel wrapped around it.

After the polymer lab, students answer the questions given below:

1. How will you classify your slime, super slurper and gluep, a solid or a liquid? Justify your answer.
2. What words can you use to describe your polymer?
3. What is viscosity?
4. What is crosslinking? How does it affect the characteristics of a polymer?
5. In making nylon, why should the two liquids not mix?

The Projects

Three-Day Food and Food Packaging Inventory

This survey is to be written and completed in each student's science journal. Each one will keep track of foods eaten for three days. While completing their journals, they have to be careful not to miss any detail in the food label. I will ask them to include all recycling symbols and chemical names and formulas written on the packages. After three days, students will synthesize their results in groups. Only one food chart will be entered per group. In groups, they will evaluate the chart by comparing it with the "Food Pyramid Guide". Then they will compare the food label notes with the plastic symbols. Each group will proceed by classifying the foods listed according to the kinds of plastic they may contain. Research on the health effects of plastics seen in the survey will follow. As they move to the completion of their research, each group will prepare a "One-Week Lunch Program Plan." They will submit this plan as recommendations for other students, teachers, cafeteria personnel, and school administrators.

Field Trip to A Landfill

One of my goals is to awaken my students to the amount of plastics in trash. To add realism to my lessons, I will take my students to one of the landfills in the Chicago area. This activity will provide a community-based learning opportunity. This trip will expose them to what is actually happening in our environment. More importantly, this will make them look at themselves from two perspectives: that of a student and a contibutor to the problem.

I will divide the class into three groups: one will focus only on "how much, what kinds" of trash are collected on a daily basis; the second group will ask questions on "classifying/sorting" schemes and how do trash separators distinguish among plastic products, and the third group will expose recycling, composting, and incineration.

Final Presentation

On the last Wednesday of the fifth week, students will be ready with posters, power point presentations, and one- week meal plans. Posters will be prepared to inform other students on the curriculum unit's final project. Each group will present their food intake results and analyses, the diseases linked to common food chemicals, and their recommendations in the form of a one-week lunch plan.

This culminating activity will be done after classes. Parents, school administrators, teachers, and other students will be invited. The final presentation will be videotaped so I and other teachers can use this as a teaching resource.