Imagine that your city would pay you $5000 to devise a plan for separating a garbage truck full of shredded mixed recyclable materials- how would you do it? This is the scenario that American High chemistry teacher Candy Sykes puts to her students in the first Honors Chemistry lab of the year.
Like many chemistry teachers, Sykes introduces her students to lab work with a separation of mixtures activity. Typically, students are given a mixture of materials such as salt, sand, and iron filings that can be separated based on their differing physical properties. Sykes adds a sustainability theme to the lesson by asking her students to separate a mixture of small pieces of aluminum cans, steel cans, PET plastic and HDPE plastic.
The sustainability theme echoes the Sykes' efforts to reduce waste across the campus and build student leadership for environmental issues. In addition to learning basic lab procedures, Sykes highlights the separate classroom sets of washable towels for hand washing and clean-up, desk-top chemical and liquid waste stations, and other classroom features designed to reduce waste.
Working in teams of four, students learn basic lab procedures such as prediction, observation, note taking, safety and teamwork as they take on the challenge of separating the 1 cm square pieces based on physical attributes like response to magnetism and density.
Unlike many labs, there is no set of standard instructions to follow- only general guidelines. Through an inquiry process, students must develop and test different ideas for separating the materials in the most efficient way possible using the tools provided.
Steel cans are quickly separated using a magnet, but separating the plastics and aluminum is more of a challenge. Although small samples of materials could be separated based on visual cues, students work diligently to engineer a process that would allow them to sort a dump truck sized load of materials.
Click through the pictures below to see more materials and student work from this lab activity.