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Now Separate It!
(from Lesson 6 - Resource Recovery)

In this lesson students explore some of the problems associated with recycling center separation by developing a separation plan based on the physical properties of the materials to be separated.

Use of the book:
Teacher background on activity: p.174-178.
Student background on reusing materials: p.179-180.
Teacher notes on activity: p.181-184.
Student instructions for activity: p.185.
Data recording/Analysis questions: p.186-188.

Materials Needed:
Per group:
4 small pieces polystyrene #6
4 small pieces of HDPE #2
4 small pieces of paper
4 glass marbles (ovoids would actually be better because they do not roll)
4 small pieces of aluminum foil
2 iron hex nuts or washers (must be attracted to a magnet)
2 pieces of wood (toothpicks or Popsicle sticks)
ziplock baggy (sandwich-size) to hold the above materials
colander, magnet, 4 straws, scissors, plastic cup of water, paper towels

p.185 on overhead transparency
p.186-188 back-to-back for participants
p.175, 186 overhead transparencies

Opening Strategy: p.182, but I would start first by asking the following questions as a hook.

How many of you recycle at home? What materials do you recycle? Use overhead transparency of p.175 – graph of household item that are recycled. Lots of info on p.174-178.

Often what is recycled depends on the cost, but also has effects on water and air quality:
· It is cheaper to recycle aluminum than to mine aluminum ore. It takes more energy to mill and refine bauxite (Al2O3) to get the Al than to recycle. Recycling saves 95% of the energy and 40% of the cost, and reduces air and water pollution.
· Making recycled paper uses an average of 2/3 less energy than pulping virgin trees. It also uses half the water, reduces water pollution by as much as 35% and reduces air pollution by as much as 74%.

Does the material you recycle at home all go into one big bin? What happens to it at a recycling plant? You will use your knowledge of physical properties to determine how to sort these materials.

Teacher may need to discuss physical properties here if not previously taught.

Procedure: p.185
Note: I don’t think it’s necessary to do the Data Recording and the Separation Plan as two separate activities so that you need two sets of materials. Integrate the parts and do together.
1. Dump test materials into colander.
2. Determine the physical properties of each material in the mixture. Record in data table p.186.
3. Design a separation process to allow a recycling company to sort the items to be recycled. You may not separate by hand. You must use physical properties as a basis for your decisions. Write the plan in the table p.187.
4. Answer analysis questions.
5. Discuss.

Recycle America in Tucson, AZ



  • Share plans with the class. Students will observe that there is more than one way to solve a problem. Also, students may catch some problems within a plan.
  • Extensions, Cross-Curricular Integration: p.183.
    Change the density of the water by adding salt.
    • How does this affect the separation process?
    • Relate this activity to others on physical properties, density, magnetism.
    • Discuss history of recycling in US, compare with other countries.
    • Investigate recycling programs available in your community.
  • Related activities – There are several in Lesson 6 related to resource recovery:
    • Not Eggsactly Decomposing, p.148-154 – students study the decomposition rates of different types of solid wastes. Note: Do this as a demo. Set up several egg cartons at different stages, ie. 1,2,3 weeks in advance.
    • Compost Columns,, p.155-173 – students create their own compost columns and watch decomposition in action.
    • Trash in the Newspaper, p.174-180, 189-199 – students make their own paper from used paper and try to remove different types of paper contaminants.
    • How Good Is Your Fuel?, p.200-212 – students investigate incineration by calculating the potential energy value of different items found in the waste stream. Note: There is a typo in this activity. The instructions omit that you also need to calculate the mass of the item after burning it (not just the original mass). Then, subtract the burnt mass from the original mass and use that value when determining the heat/mass ratio.
  • The Garbage Gazette: p.213-214.
    • “ Fluff Up A Milk Jug For A Good Night’s Sleep?” – recycled materials
    • “ Natures’ Garbage Disposal” – worms in composting (vermicomposting)

Southwest Environmental Health Sciences Center
University of Arizona College of Pharmacy, Room 244
PO Box 210207, Tucson, AZ, USA 85721-0207

Funded by NIEHS grant # ES06694

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Last update: November 10, 2009
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