HABITS ARE WORTH FORMING!

MASTER TEACHER      Jose Silguero

GRADES    3 - 5

OVERVIEW
Students will be introduced to the fascinating world of crystals. They will discover how crystals form and why they form as they do. Students will create rock candy to observe crystals forming.
Students will construct models of crystals.

ETV SERIES
3-2-1 Classroom Contact - They're Habit Forming

LEARNING OBJECTIVES 
Students will be able to:
* examine and classify types of crystals and list some of their properties.
* create rock candy to observe the formation of crystals. 
* replicate the crystals by making crystal models.

MATERIALS
measuring cup
hot plate
large pot
spoon

Per student 
clean baby food jar
pencil
4 inch piece of string
paper
colored pencils
worksheet - Activity sheet #1-7

VOCABULARY
This list may be posted around the room or near the area that the experiment "creating the rock candy"  will be executed.
crystalographer - people who study crystals
habits - the shape of crystals

molecule - smallest particle that makes up a crystal
minerals - a solid, crystalline chemical element or compound that results from inorganic processes
isometric - cube shaped
octohedron - diamond shaped
pyrithohedron - pentagon shape 
rhombohedron - hexagon shape

PRE-VIEWING ACTIVITIES
Ask students if they have ever seen a piece of quartz or if they have ever noticed the shape of table salt or raw sugar. Give each student a small amount of salt or raw sugar. Ask if they can observe any prominent shape to either of them. The raw sugar is an ideal way to see the cube-like shape of the sugar crystals. Have them hypothesize whether or not they will be able to "grow" crystals in the form of rock candy.

FOCUS FOR VIEWING
Hand out Worksheet #1  To give students a specific responsibility while viewing, say "While you are viewing the video, look for the answers to questions 1 - 5 on the worksheet.  Identify at least eight kinds of crystals, look for two characteristics of crystals and learn what a cystalographer does.  Listen for the definition of a habit and observe what type of habit a salt crystal has."

VIEWING ACTIVITIES
Begin the video at the beginning where the screen shows  a little girl pouring sugar into a half-filled fish bowl of water. The girl says, "Oh, excuse me. I've got to get this going." Pause tape when the girl says, "Crystalographers would say that salt crystals are cube shaped and these are salt crystals."  The screen shows a magnified picture of grayish salt crystals. At this time answer questions 1-5 on Activity Worksheet #1 through group discussion and guided practice.  Ask your students to name eight kinds of crystals.    Resume video.. The screen should show pyrite crystals immediately after the salt crystals. Continue the video until the girl finishes checking the bowl of growing crystals. She says,"I'll come back to this later. Stick around." Pause the video when you see the girl walking on a trail in the woods holding a tripod and a camera.  Fast forward until you see the girl standing behind the rock crystal experiment.  Play.  Tell  the students to pay close attention because they will use this information to answer questions 6 - 9.  Stop the video when the girl says that snowflakes are formed in the chaos in the clouds.  Questions 6 - 1 on Worksheet #1 can be answered now.

POST-VIEWING ACTIVITIES
Say "Now that you have seen how crystals are formed, you are ready to perform the Rock Candy experiment. Use the information you have learned to answer the activity sheet questions."  The students should now understand that crystals are comprised of many different shapes.  By viewing the video, they have developed a visual image to go by as they start to construct their own crystal models.  As the students create their own rock candy, visual learners can refer to the video to help them with the procedure.

ACTION PLAN
Have a geology professor or a geologist from a local college or university come and speak to your class. Perhaps your class could make a visit to his classroom.

EXTENSIONS
Language Arts
Students may watch the entire video  and write a summary of it. Students may research and write an essay on  the study of crystals.  To check for understanding, the teacher can write the directions for making crystals on sentence strips, mix them up and then have the students place them the correct order of the procedure.

Science/Math
The students may measure out the materials involved in creating the rock candy.   Review: Is the  liquid  a mixture or a solution?   Measurements may be taken of the rock candy crystal, how long, how wide, etc.

Art
Students can create models of crystals

Music
Students may write their own rap or song 

Internet Connection
http:info.er.usgs.gov:80/education/index.html
http://niu.niedu/bthu/nlu/eight/es/Homepage.html

Careers
You can have professionals such as geologists, jewelers and other science teachers come and speak to your class. The students may also go to other classrooms and create the different crystals and crystal gardens for smaller children. It will awe them!

Bibliography
Rocks and Minerals by R.F. Symes and Colin Keates
Crystals and Gems by R.F. Symes and Colin Keates
 
 

Activity #1 
Habits Worth Forming!
Answer these questions while you watch the accompanying video.

1. Name eight kinds of crystals. _____________________________________________________________
2. What two characteristics do crystals have?
__________________________________________________________
3. What are crystalographers?
___________________________________________________________
4. What is a habit?
___________________________________________________________
5. What type of habit does salt have?
___________________________________________________________
6. What is the structure of the crystal?
____________________________________________________________
7. How does the little girl paraphrase what crystals are?
____________________________________________________________
8. What shape do you think the molecules have that make up the rock candy?
_____________________________________________________________
9. How many sides does a snowflake have?
_____________________________________________________________
10. Why do you think that the sugar crystals form as they do on the string that was 
       dipped into the sugar water?
____________________________________________________________
 
 
 
 

Activity #2
Rock Candy
In this activity , teachers and students will create rock candy to observe the formation of crystals.

Procedure:
The teacher will mix 16 cups of sugar with  8 cups of water.  Warm over medium heat. 
When the 16 cups of sugar has dissolved,  add additional sugar until no more will dissolve.
Remove pot from the heat and allow the contents to cool until lukewarm.
After the sugar  mixture has cooled, the teacher will pour the mixture into clean baby food jars
Each student needs a 4-inch piece of string tied around the center of a pencil.  Place a pencil across the rim of each jar, allowing the string to hang down into the sugar mixture.  Set the jars aside and leave them overnight.  Within a few hours, crystals should start to form.. Discuss this with your students.  The next morning students should observe their jars and discuss what has occurred overnight.  Finally, pull the rock candy out of the jar and enjoy!

Activity 3  HEXAGONAL HABIT   EXAMPLE: CALCITE
Copy the patterns of the cube, hexagonal, octohedron and pyrithoedron crystal models onto a stiff piece of paper.  Have the students cut out, fold and tape the tabs to create models of some mineral crystal habits.

Activity 4     CUBE HABIT          EXAMPLE:  SALT

Activity 5   PYRITHROHEDRON HABIT EXAMPLE:PYRITE 

Activity 6 OCTOHEDRON HABIT  EXAMPLE: DIAMOND

Activity 7
Crystal GardensRocks are mixtures of minerals, and minerals form crystals.  Every mineral has its own unique crystal habit.  Grow your own crystals using these sugar and salt recipes. 

Materials
Boiling water sugar
salt food coloring
vinegar small pieces of charcoal briquette
drinking glasses shallow glass container
measuring cup tablespoon
clean string or thread clean paper clips
pencils, sticks, or straws paper towel
magnifying glass

Procedure
1.  Rock Candy   Fill a drinking glass about one third full of boiling water.  Stir sugar into the water until no more will dissolve.  A large amount of sugar can be dissolved in a little water.  The ratio is about two parts sugar to one part water.  The result will be a thick syrup.  Tie one end of a peice of string to the middle of a pencil and the the other end to a clean paper clip.  Wet the string and paper clip and pull them through dry sugar so that grains of sugar stick to them.  The grains of sugar on the string act as "seed crystals."  Place the pencil across the rim of the class so that the paper clip suspended midway in the solution.  Put the class where it won't be disturbed.  Cover it loosely with a paper towel to keep out dust.  After several days, crystals will form around the paper clip and string.  If the water evaporates slowly, the crystals will be quite large.   Use a magnifying glass to examine them.  What shape are the crystals?  Compare the shape of the crystals to the shape of some grains of sugar.  How did the sugar crystals form?  Taste the crystals.  Why do you think they[re called "rock candy"?

2. Salt crystals Follow the same procedure used for sugar crystals.  Less salt is required.  Use one part salt to one part water.  How do salt crystals look compared to sugar crystals?

3. Crystal Garden Place several small pieces of charcoal briquette in a glass container.  Place 250ml of boiling water in a measuring cup.  Stir salt into the water until no more will dissolve.  Ass two tablespoons of vinegar.  Pour the mixture over the charcoal briquette pieces.  The charcoal should stick up out of the mixture.  Put several drops of food coloring on the charcoal pieces.  Place the container where it won't be disturbed.  In a few weeks a colorful crystal garden will grow.  The crystals are fragile so don't move the container.  Do not taste!!!

Updated:  April 01, 2008