The Life and Times of Percy Julian

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Activity 7A.7 (Lab Activity)
Assessment: A Challenging Separation

Note to Teachers: There is no corresponding student version of this separation activity on the site. This is an in-class activity.

Lesson Overview This activity combines several types of separations into a single separation activity. It can be used to assess what students have learned from the other separation activities. In particular, before doing this challenging separation, you should have completed the in-class lab activities 7A.1 (Separating Marbles), 7A.3 (Separating Plastic and Metal Beads), and 7A.5 (Magnetic Separation) with students. Since the mixtures will contain more than two components, students will need to use more than one method to achieve separation. Student groups must choose which equipment will separate their particular mixture.
Learning Objective Students will apply what they’ve learned about separation techniques, namely, that they are based on differences in properties of the substances that are mixed together. They will use their problem-solving and logical-thinking skills.
Lesson Concepts Different physical properties of substances in a mixture allow for separation techniques that use the varying physical properties (e.g., particle size, density, magnetic attraction).
Materials Required

Per lab group:

  • Four 8-oz. paper or plastic cups
  • Approximately 5 of each of the following mixture components:
    • Large glass marbles
    • Small glass marbles
    • Plastic beads, same size as small glass marbles
    • Metal beads (steel ball bearings or BBs)
  • The following tools for use in the separation:
    • Permanent magnet
    • EITHER a plastic-container filtering apparatus as prepared for Filtering Method A in Activity 7A.1, Separating Marbles, OR a glass-jar filtering apparatus as prepared in for Filtering Method B in Activity 7A.1, Separating Marbles
    • Bucket or other container
    • Aluminum pie pan
    • Water
Safety

Students should wear safety goggles. Students should be cautious using glass materials (marbles and jars).
Skills Required

Any skills learned in the previous separation activities (7A.1 through 7A.6).
Time Required

After the pre-lab review of separation techniques, this activity should take 15–20 minutes to carry out.
Student Ability Level and Grouping

This activity may be done by middle school students working in groups of two or three.
Pre-lab
  1. Before class, prepare one mixture of the four components in an 8-oz. cup for each group.
  2. Review with students the different separation techniques used thus far and the basis for their use.
Procedure Notes
  1. Distribute the prepared mixtures to the lab groups. At the same time, give each group three additional 8-oz. cups (empty). Explain that by the end of the lab, they should have four cups, each of which contains one of the four components of the original mixture.
  2. In a prominent place at the front of the classroom, spread out the various tools the students will need to separate their respective mixtures: the magnets, aluminum pie pans, various containers, and water.
  3. Tell the students that their task is to separate their group’s mixture using the tools provided. Remind them that they cannot separate the components of the mixture by hand but must use the tools and the techniques they have learned in previous activities.
  4. Have the students write out the steps of the procedure they intend to follow on the Investigation Record Sheet for this activity.
  5. Check and approve all procedures before allowing the students to begin.
  6. Have students record their observations on their Investigation Record Sheets as they carry out their procedures.

Examples of student procedures:

Example A:

Step 1: Pour the mixture into an aluminum pie pan and use a magnet to extract the steel beads. [property: magnetic attraction]

Step 2: Put the remaining mixture into a container of water so that the plastic beads float to the top and can be scooped off. [property: density]

Step 3: Use a container apparatus as a filter to separate the large marbles from the small marbles. [property: particle size]

Example B:

Step 1: Pour the mixture into a container filled with water. The plastic beads should float to the top and be scooped off. [property: density]

Step 2: Drain the water off the remaining mixture and pour the mixture into a container apparatus (filter) to separate the large marbles from the small marbles and the steel beads. [property: particle size]

Step 3: Pour the steel beads and small marbles into an aluminum pie pan and use a magnet to extract the steel beads, leaving only the small marbles. [property: magnetic attraction]
Post-lab

Students should describe how their method of separation is an application of the basic idea behind separating mixtures on their Investigation Record Sheets.

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