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ACTIVITY in Observations, Separating Mixtures, Physical Properties, Introduction, Matter, Mixtures. Last updated August 01, 2023.

Summary

In this activity the students will separate a mixture and classify objects by their physical properties.

Grade Level

Elementary School

Objectives

By the end of this activity, students should be able to

  • Define a mixture.
  • Understand mixtures can be separated.
  • Classify matter by physical properties such as magnetic and non-magnetic.

Chemistry Topics

This activity supports students’ understanding of

  • Separating a Mixture
  • Physical Properties
  • Magnetism

Time

Teacher Preparation: 10 minutes

Lesson: 30 minutes

Materials

(Per group)

  • Container to hold sand (preferably clear)
  • 1 pound of sand
  • Variety of small objects to hide in the sand box (Examples: paper clips, coins, plastic and wooden cubes, balloons, screws, washers, buttons, etc.)
  • Magnets
  • Colored Pencils

Safety

  • No specific safety precautions need to be observed for this activity.

Teacher Notes

  • This activity is designed for third grade students, but could easily be adapted for 1st and 2nd grade students.
  • A mixture consists of two or more substances that are physically intermingled, but not combined chemically. It can be separated into its individual components by physical means, and often retains many of the properties of its components.
  • The physical properties of matter can help you determine which tool, such as a magnet, can best help to separate a mixture.
  • The pre-lab questions on the student handout could be asked to the whole class before the lab to start a discussion, or students can turn and talk to answer the questions and then share their ideas with the group to create more connections with prior knowledge.
  • Prepare the containers in advance by hiding the objects in the sand.
  • Optional: Discuss each object with the class and have students make predictions about the physical properties of each, and if the object to be attracted to the magnet or not.
  • Classroom management tips: groups of three to four students work best.
  • A clear plastic shoe box works best for this activity because students can manipulate the sand to look for the hidden objects, and see how it looks before and after.

For the Student

Background

A mixture consists of two or more substances that are combined, in a way that the substances can be separated and removed from the mixture. If you combined raisons, M&Ms, and chocolate chips, that would be a mixture because you could physically separate the different substances. But if you combined vinegar and baking soda and a chemical reaction took place, this would not be a mixture. The substances combined chemically and became something different so the original substances could not be separated. Magnetism can sometimes be used to separate the different parts of a mixture. Magnetism is a force that can attract (pull closer) or repel (push away) objects that are made of a magnetic material.

Pre-lab Questions

  1. What do you observe in the sandbox?
  2. Can the objects inside be separated from the sand?
  3. How would the objects and sand change if they are separated?
  4. What tool(s) can be used to separate the objects?
  5. What type of objects could be separated with the magnet?

Objective

Use your knowledge of magnetism to help you determine how to separate the mixture in the sandbox.

Procedure

  1. Draw what you observe in the sand box (before exploring) in the space below.
  2. Use the magnet as a tool to separate as many objects as possible from the sand box.
  3. Use your hands to separate the remaining objects.
  4. Draw your observation after exploring in the space below.

Results

Before


After


Classify: Write the name of the objects that you could separate from the mixture using the magnet in the “magnetic objects” column, and the objects that did not attract to the magnet in the “non-magnetic” column.

Magnetic objects

Non-magnetic objects

Analysis

  1. Did the components of the mixture change from “before” to “after”?
  2. How did the magnet help separating the mixture? What can you conclude about using tools to separate mixtures?
  3. What characteristics did you observe in the magnetic objects? What do all magnetic objects have in common?
  4. What characteristics did you observe in the non-magnetic objects?
  5. Is it possible to create the same mixture again and separate it?
  6. How can the physical properties of objects be helpful? Think about other physical properties, such as size, what other tool could you use to separate the sand from the objects?
  7. What physical properties were observed in this investigation?
  8. Think about another situation where you needed to separate a mixture, what physical properties help you decide which tools that you need to use?
  9. Read the next situations and talk to your partner to decide how to separate the mixtures:
    1. Your mom asks you to help her with the laundry. She reminds you to make sure to wash like colors.
    2. You are helping baking a cake, and the recipe requires that you separate the egg yolk from the egg white.

Research Extension

How is oil separated from the ocean water after an oil spill? What tools are used? Are these tools related to oil and water physical properties?