Teachers TryScience

Before the Lesson

• Gather enough trash cans/bins to store your classroom trash for a week.
• Make large, easily readable labels (Food, Paper, Plastic, Glass, etc.) for each trash container.
• Discuss your plans with the school custodian or a substitute to ensure that your trash stays in your classroom all week. (Do not skip this step! Awell-intentioned custodian or substitute may throw away your activity materials,thinking they are doing you a favor!)
• The trash collection period should run for 5full class days. Day 6 should be for the lab portion of the project.
• Make a large class data chart similar to the data collection chart on the Let's Talk Trash Worksheet.

  Let's Talk Trash Worksheet
  

With the Students

Before Day 1 of Trash Collection

• Begin with a class discussion. Ask students: What do you throw away? Do you throw away soda, milk or water bottles, candy and food wrappers, boxes, and/or plastic or paper bags? Does the trash collector remove bags or cans of garbage from your home — and on a larger scale — your neighborhood every week? Do you wonder where all this trash goes? Where is it hauled to after it leaves your home/neighborhood? What happens to it after it gets to where it’s going? This video on Asking Good Questions might help inform your instruction.

  Asking Good Questions video
  
  

• Describe the project to the class. Discuss the different types of trash you will collect and how you will collect it. (Note: collect only trash from the classroom. For example, do not ask the students to bring their trash back from the lunchroom or from home.) Show students where the different labeled trash containers will be located in your classroom for the week. Demonstrate that plastic goes in the container labeled "Plastic," paper in the container labeled "Paper," etc.
• Collect trash for 5 full school days.

Day 6: The Lab Day

• On the sixthday, divide the students into groups of 4. You may want to view this video on Group Work to inform your instruction.

  Group Work video
  
  

• Distribute the Let's Talk Trash Worksheet to each student.
• Ask students to predict how much trash (total mass) the class generated this week and predict the amount of trash in each of the categories (e.g., food, paper, plastic, etc.).
• Assign each group one portion of the trash as their lab materials. Distribute a pair of gloves to each student.
• Distribute three trash bags to each group, and ask each group to sort their trash using the trash bags. Remind them to wear their gloves! They should sort their trash into three groups: recyclable, non-recyclable and re-useable. (Note: you may need to discuss the differences between these groups; see Figures 1-4). Do not sort any food waste!

• Ask each group to find the mass of each pile of trash. Instructthem to record their units (kg.or lbs.) on their own data table and to round to the nearest ½ unit (this will depend on the scale). You also may want to have the students look at the fraction and decimal representations of the different categories in addition to the percentages.
• Once students have completed their data table, ask each group to share their results with the class. Student teams can write their mass onthe class data sheet, whetheron the board or overhead.
• Ask students to complete the “Analysis”section of their worksheet. If there is not enough time, they can finish the graph for homework. While the worksheet asks for a pie graph, you might want to view this video, Representing Data, for other ideas.

  Representing Data video
  
  

• Have students pair up within their teams and work on the “Discussion Questions”portion of the worksheet. After students have finished, discuss answers as a class.
• Using the “Conclusions”section of the worksheet, assign one student in the group to be the recorder. Then ask a student to toss out an ideafor an engineering solution. Next, another person in the group provides an idea that builds on the first. Go around the group in this fashion until all students have put in enough ideas to put together a designas a class. You can use the information on the Recycle Now web site to help students understand some real world engineering applications.

Safety Issues

• Have students wear gloves when sorting trash.
• Remind students that the plastic bags should not be played with (i.e., put over their own or others' heads) and should only be used for sorting the trash.
• Be sure glass items are not broken and that metal items do not have sharp edges.
• Be sure to seal the food trash bag each day in order to prevent health hazards. Another option is to weigh the food trash each day and keep a running record of it.
• Be sure all containers are rinsed before being placed in the waste bins (especially food containers).

Troubleshooting Tips

• You may need to review how to calculate percents and/or how to create pie charts.
• Save the recyclable and re-useable materials for activities in later lessons.