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Crystals

 

crystals.png

Grade Level: Grades 4 and up, supervision required.
Subject: Science, Language Arts, Mathematics, Art
Duration: 1 Week
CELs: Communication, Numeracy, Technological Literacy, Independant Learning

Objectives:

  1. The students will learn that there are a number of ways to grow crystals.
  2. The students will observe that some crystals have different shapes.

Definitions:

Crystals: The outer shape a mineral takes if allowed to grow freely.

Crystal Shape: When crystals of a mineral are formed they belong to one of the six crystal systems: cubic, hexagonal, tetragonal, orthorhombic, monoclinic, or triclinic.

Activity #1: Crystal Gardens

This activity can be done as a group project or as a classroom demonstration.
There needs to be space provided so the materials will not be disturbed once it is set up.

**Note:** Laundry Blueing will stain and Ammonia needs care in handling.

Materials:

  1. 60 ml laundry blueing
  2. 60ml water
  3. 75 grams of salt
  4. 10 ml of ammonia
  5. 1 charcoal briquette
  6. 500 ml beaker (an aluminum pie plate will work)
  7. 250 ml beaker
  8. food colouring (Optional)

Method:

  1. Mix the laundry blueing, water and salt together in the 250 ml beaker.
  2. Add the ammonia.
  3. Break up the charcoal and put 4 or 5 pieces about the size of a small matchbook into the 500 ml beaker.
  4. Pour the mixture from the 250 ml beaker over the briquette pieces.
  5. Sprinkle a few drops of food colouring over the pieces of briquette. (Optional)

Questions & activities:

  1. How long does it take before you observe any crystal growth?
  2. Describe the crystals. These crystals are extremely fragile - take care!
  3. Carefully draw the Crystal Garden. 4. Research: Draw diagrams of the 6 crystal shapes.

Activity #2: Observe crystal shapes with magnifiers or a microscope.

 

Materials:

Microscopes, magnifiers, table salt, potash samples, sugar, quartz crystals, any other crystals the teacher may have access to. Crystal sets can be purchased from any Science Supply Company.

Method:

The students can observe and draw the crystal samples as they observe them.

Questions and/or activities:

  1. Describe what you see in your own words.
  2. Research how crystals are formed.
  3. What are the 6 shapes that crystals can occur in?

Activity 3: Growing sugar crystals

You may substitute salt, copper sulphate, alum, Epsom's Salts, etc. for the sugar. This can be a classroom demonstration, a group activity or an individual activity. It will depend on safety, time and the availability of materials.

*CAUTION** Copper sulphate needs to be handled with care - make sure the students wash their hands carefully if they touch copper sulphate.

Materials:

  • A container to boil water in (An electric tea kettle works well)
  • A 250 ml beaker
  • sugar
  • A thick glass jar
  • a stick
  • cotton string
  • a weight to hang into the jar
  • petri dishes (or equivalent)

Method:

  • Boil the water, pour into a container, add sugar and stir. Keep adding sugar until no more will dissolve.
  • When the solution has cooled, pour it into the glass jar.
  • Rub some sugar onto the string so that some crystals stick to it.
  • Tie one end of the string around the stick and drop the other end (with the weight attached) into the sugar solution. Rest the stick on the rim of the jar.
  • Put the jar in a place where it will remain undisturbed.
  • Leave it for a few days to see what will happen.

Alternate Activity:

  • Repeat #1 from above.
  • Pour the solution into some flat petri dishes, place uncovered in a safe place and check from time to time. Copper sulphate crystals will form very nicely using this method.

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