This lesson invites students to explore properties of matter as they apply to cans, specifically aluminum cans. One of the easiest ways to identify different can types is through their response to magnets. Magnets will not attract aluminum but will attract other kind of metals containing iron, such as steel. Other ways to distinguish them include appearance, weight, color, resistance to corrosion and temperature conductivity.

Extended Materials List for Each Station
Station 1: Magnetism, Weight, Flotation

• Magnets, magnetic compass, pan balances or scales, bucket of water, stopwatch or watch with second hand.
• Three similarly sized empty cans labeled #1, #2, #3: (1=aluminum, 2=steel, 3=bimetal). An example of a bimetal can is a snack-size canned fruit can.
• "Station 1" card with procedure and focus questions.

Station 2: Appearance, Corrosion Resistance (do ahead of time)

• Magnifying glass, scissors, books
• Three similarly sized empty cans labeled #1, #2, #3 (1=aluminum, 2=steel, 3=bimetal).
• Two jars (with lids) labeled #1, #2; two aluminum and two steel nails without any signs of rust. Prepare this part 4-5 days ahead of time:
  • Put two aluminum nails in jar #1. Sprinkle the nails in the jar lightly with water, then put the lid back on the jar.
  • Put two steel nails in jar #2. Sprinkle the nails in the jar lightly with water, then put the lid back on the jar.
• "Station 2" card with procedure and focus questions.

• aluminum nail and steel nail of same size
• matches
• candle in candle holder
• stopwatch or clock with second hand
• rubber-handled pliers
• small amount of candle or sealing wax, tweezers. Prepare this part ahead of time:
  • Break off two pieces of wax, each about the size of a pencil eraser.
  • Using tweezers, hold each piece of wax in a candle flame until soft. Attach one piece of wax to the middle of each nail.

• bucket of ice
• three similarly sized cans labeled #1, #2, #3 (1=aluminum, 2=steel, 3=bimetal) and filled halfway with water
• thermometer

1. Prepare stations in advance.
2. Begin a discussion of properties of matter by recalling how students examined properties of packaging, specifically the activity in which they suggested different uses and purposes for different types of packages. Open discussion about properties of metal cans.
3. Explain the procedure for using the stations. An example of how you might do so while at the same time "rehearsing" the experiments is given below:
   1. Magnetism: Hold up a magnet. Ask for a show of hands of students who have experimented with magnets. Did they notice things magnets attract? Explain that magnets are pieces of iron or steel or other materials that can attract certain metals. Experiment with paper clips, tacks and rubber bands to show how some materials are attracted to magnets while others aren't.
   2. Appearance: Show can samples. Explain that many cans look similar, but they can be identified by color, weight, recycling symbols, rims around lids, etc. Explain that as they study three types of cans they will notice certain characteristics about how each can is made that will help them learn what each is made of.
   3. Weight: Tell students they will learn that one type of can metal is heavier than another. Show them how to use the scale. Ask them to predict which can they think will be heaviest, and tell them they'll get to test their prediction at Station 1.
4. Divide the students into groups. Give one handout to each student. Have them take a pen or pencil, their science notebook, and a handout with them to each station to conduct the investigation.
5. While students are engaged at Stations 1 and 2, you conduct activities at Station 3 as indicated below:
   1. Heat Conduction
      • Assign one student to be the timekeeper. Light the candle.
      • Holding one end of nail 1 (aluminum) with the pliers, place the other end of the nail in the candle flame. Have the timekeeper time how long it takes for the wax to melt.
      • Repeat the experiment with nail 2 (steel). On which nail did the wax melt faster?
   2. Chilling
      • Assign a different student to be the timekeeper.
      • Measure the temperature of the water in each can (they should both be room temperature).
      • Place each can in the bucket of ice. Measure the temperature of the water in each can at 1 and 2 minute intervals for about 5-10 minutes. Record the temperature of each can's water.
      • What do you notice? Compare this with the heat conduction experiment. What did you learn about each metal?
   3. Tell the students you are going to state properties of aluminum, steel and bimetal cans, and their job is to figure out which can is which metal. As soon as they know which can it is, they should raise their hand.
      1. Aluminum (1): not magnetic, lightest weight, conducts heat fastest, chills fastest, no rim on bottom, finely brushed appearance, labels printed on can, no seams
      2. Steel (2): magnetic, heaviest, conducts heat slower, chills slower, rim on bottom, body on some cans has rings or ribbing, usually has a paper label, often has a seam
      3. Bimetal (3): body is magnetic but lids are not, heavier than aluminum but lighter than steel, bottom has rim but is not finely brushed, usually has a paper label
   4. Have students explain how manufacturers would use what they know about metal properties to make decisions regarding packaging items in cans. For example, why put beverages in aluminum cans rather than in steel cans? What products would be suitable for steel cans? For bimetal cans? Why choose a can at all, compared to some other sort of packaging?
   
   WRAP UP

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   (Students can choose one of the following activities.)
   1. Tell the students that because they are made of different metals, cans should be sorted before they go to the recycling center. Ask the students how they could use what they've learned about can properties to sort cans. Students can work in teams to create an efficient method (fastest with least waste of time or energy) to sort cans for recycling. Have them explain their choices. Let the class choose what they think is the best procedure.

   2. Give students bags of cans (of all types) to be sorted for recycling. Have students break into groups, create a procedure (as above), and test it by using it to sort the cans. Time each group. Discuss their conclusions. Then drop off the cans at the recycling center or at appropriate pick-up points.
   
   
   EXTENSIONS

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   Note that the following products can be made of aluminum: airplanes, ice cube trays, TV trays, baseball bats, beverage cans and cars. Have students choose three products made of aluminum and explain how the properties of aluminum make it a suitable material for those products. This activity could be made into a poster with pictures of products mounted on it and incorporated into a display entitled "Aluminum All Around."
   
   
   REFERENCES

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   Parts of this lesson were adapted from "Solving the Can Can Mystery," 4Rs Project: A Solid Waste Management Curriculum for Florida Schools, 1990, page 69.