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Lesson Plans
You’ve Got to Be Cool to Make Igneous Rocks
OverviewProcedure for teachersStudent Resources and Materials

Prep for Teachers

Prior to the teaching, bookmark all of the Web sites used in the lesson. Load Shockwave for the extension activity. Cue the videotape Earth Revealed Introductory Geology Episode 6, close to the beginning of the video on the black and white picture of James Hutton as the narrator says, “The study of igneous rocks began in the 1780’s.” When using media, provide students with a FOCUS FOR MEDIA INTERACTION, this is a specific task to complete and/or information to identify during or after viewing of video segments, Web sites or multimedia elements.

Set up the bags with the building blocks and paper. Put this in front of the room to give out to students as they come in. Photocopy and cut up one web task sheet per group. Photocopy student sheets Set up a basket with everything else students will need. A microscope or good magnifying glass is needed to view the salt solutions.

Prepare a saturated solution of NaCl (table salt) by taking the 120 g of salt and putting it into 300 ml of hot water. Leave overnight then drain the liquid into a clean 400 ml beaker the next day. Label the beaker and place three to six eyedroppers in it.

Prepare a saturated solution of CuSO4 (copper sulfate) or CuSO4.H2O by taking the 500 g of salt and putting it into 1 L of hot water. Leave overnight then drain the 100 ml of the liquid into 10 clean 250 ml beakers. Students will tie a string to one crystal of copper sulfate and the other end of the string to the center of the pencil. Make sure the string touches the bottom. Each group of students will take one beaker and place it in a different place in the classroom (or school) for about two weeks. There should be one or two beaker not used. Label these beakers and place three to six eyedroppers in each. (Nine beakers will be used in Culminating Activity #2 and 1 will be used in the Learning Activity Step 7.)

Prepare the room for ventilation. You will need some sort of ventilation when using the artificial snow. Note the warnings on the side of the can. You may decide to do this in front of an open window with the air blowing out. (Check student allergies before using the snow.)

Create student groups so students of different functioning levels are mixed and the groups are between 2 and 4 students. These groups will be broken down in to Internet groups. The ideal is to have each student at their own computer, you may have one student from two to three groups working on the A site together, and so on with the other sites.

Introductory Activities: Setting the Stage

Step 1:


Group students into teams of two to four. As students come in give the group a bag of building blocks and one or two pieces of paper and ask them to write down their name, date and time and quickly start to build a structure. (Do not use the word “building.”) One or two people will construct the structure while the other one or two will draw a picture of the structure on the paper.

Step 2:


Give three minutes and then ask them to stop and put the time on the paper.

Step 3:


Discuss the following with the class. How big is the biggest structure? (Use the number of blocks in the structure to determine big.) Which structure is the most dense? (A solid building with no inner space) Which structure is the strongest? (Regular solid cube with no windows or inner space.) You were making igneous rocks. How is this activity like making igneous rocks? (Pose the questions but do not answer it. This will be answered in the learning activity.) Note: this activity will be finished in the learning activity steps 4-6.


Learning Activities

Web Based


Step 1:

Hand out Student Worksheet #1: Rocks and say the following, “The name of this lesson is You Got to Be Cool to Make Igneous Rocks. I know it is a bad joke but what do you think that means?” (Accept any answer) “Before we can fully appreciate my sense of humor we need to learn more information about Igneous Rocks.” Give each student his or her assignment.

Subdivide the group by giving each member of the group a different Web Task Sheet with their letter A, B, C or D on it. Group E is used for students who may have special learning needs. If you wish you may just use two groups - Group A and Group C. These are the minimum two sites that must be used. Students may also be broken into two groups by giving one group A and B and the other group C and D. Also require the students to rate the sites. Realize the more sites you give your students the longer it will take them. To do this in a limited amount of time, give each student one site. Use http://geollab.jmu.edu/Fichter/IgnRx/selftest.html to allow the student who finishes early to keep exploring (this is optional). Cut up and give out the Web Task Sheet.

Letter A people will use http://duke.usask.ca/~reeves/prog/geoe118/geoe118.012.html
to answer questions 3, 4, 7, 8, 11, 12, 13, 14, and 18.

Letter B people will use http://seis.natsci.csulb.edu/basicgeo/IGNEOUS_TOUR.html
to answer questions 1, 2, 3, 4, 5, 6, 11, 12, 13, 16, and 17.

Letter C people will use http://www.dc.peachnet.edu/~pgore/geology/geo101/igneous.htm
to answer questions 1, 2, 5, 6, 11, 12, 13, 14, 15, 16, and 17.

Letter D people will use http://www.geolab.unc.edu/classes/Geo11L_Caleb/igneous.html
to answer questions 1, 2, 3, 4, 13, 14, 15, 16, and 17.

The site http://sln.fi.edu/fellows/payton/rocks/create/igneous.htm may be used for Letter E group (students who may have special learning needs). It can be used to answer questions 1, 2, and 19. Note: sites should be bookmarked ahead of time.

Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to define and answer the questions on the Student Sheet #1 using the Web Task Sheet. Students have three tasks that must be done in order. The first part is to read the directions on the Web Task Sheet. Each of you will receive a site and the questions on the Student Sheet you will answer. The second part is to find your site and do your research, fill in your sheet and rate the site. Is the site appropriate? Does it help you answer the questions? The third part is to meet with your group, exchange answers and take them to your site and show them what you found.

Step 2:

Have students work for 10 minutes and then stop them. If students finish early give them one of the extra sites. After about ten minutes have students come back into their original team and compare their answers. Students are to show their other student members how they found their answers on the Web and explain all the answers to each other.

Step 3:

Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to answer, “What does each of the vocabulary words mean? What three factors are used to classify igneous rocks?” (Minerals, where it cooled, texture.) It is OK to get other similar answers. You are looking to review by showing students where to find the information. Visit the sites to review student answers. Students should be used to show others what they learned at their sites.

Ask all students to log on to each of the sites and be able to explain how they got their answers to the rest of the group. Answers should be similar to the following. Magma is molten rock below the earth’s surface while lava is molten rock at the earth’s surface. Extrusive rocks are formed at the earth’s surface; examples are Rhyolite, Andesite, and Basalt. Intrusive rocks are formed underground; examples are Granite, Diorite, and Gabbro. Pyroclastic Ash and Pyroclastic bombs are small and large particles thrown out when a volcano erupts. A vertical sheet of igneous rock is a dyke while a horizontal sheet of igneous rock is a sill. Coarse-grained is larger than 1 mm while fine-grained is smaller than 1 mm (some say 2 mm). Porphyritic texture is a rock with small and large grains. Vesicular texture has spaces or gas pockets in the rock. Glassy texture looks like glass. Felsic rocks are light colored low-density rocks (that can contain aluminum.) Mafic rocks are dark high-density rocks (that contain iron and magnesium.)

Open http://sln.fi.edu/fellows/payton/rocks/create/igneous.htm to see a good animation showing how igneous rocks are formed and get four examples of igneous rocks. This site is the only one that gives igneous rocks and their common uses. Granite is used for long lasting monuments and trim for buildings. Pumice is used as a decorative landscape rock and is ground up and put into soap (lava.) Obsidian is volcanic glass and has been used as arrowheads by Indians or a decorative stone. (The name Obsidian is not given in the Web site. Lead the class to the function of obsidian.) Note: You know your class and the amount of review they need. You may decide to only review the topics that gave your students the most problems and show them the animation.


Day 1

Step 4:

Have students take out all the building blocks and place them on the table so they can all reach them. Each student is to build his or her own structure when you say start and build until you say, “Stop.” Students are to start with their hands on their laps.

Step 5:

Once students’ hands are on their laps say, “Start, stop.” (Don’t pause – you are trying not give them enough time to build a structure.) Ask how many blocks are in the structure they built. Answers should be zero or one. Tell the students you know that wasn’t fair, but you will give them another chance. Tell them to put their hands on their laps. Say, “Start,” and then in about ten to fifteen seconds say, “Stop.”

Step 6:

Students are to look at the three structures they built. The three structures are the large structure they built for three minutes as they came in, the structure they built for 0.1 second when you said “Start–stop,” too quickly, and the fifteen second structure. If the blocks are molecules, and a couple of blocks make a crystal, which structure was the biggest (had the most blocks) and which structure is the smallest (had the least blocks)? (The three-minute structure has the most blocks and is the biggest, while the 0.1 second structure is the smallest with no blocks.) Why was the three-minute structure the biggest? (They have more time to organize the blocks.) Put the following words on the board: glassy, fine-grained, coarse-grained. Ask the students, “Using the structure you built when you came in for three minutes, the structure you built for 0.1 second and the third structure you built for 15 seconds, which of these structures could be classified as glassy, fine-grained or coarse-grained?” (Here we are acting as the crystal builders for a rock. The first structure we built was coarse-grained: since there was more time to build the structure the structure had bigger crystals or more blocks. The second structure we tried to build didn’t have any crystals and is called glassy. Glassy rocks cool so rapidly at the surface that they have no time to form crystals. This structure is glassy since it has no crystals. The third structure we built had crystals, but small crystals. This rock formed quickly near the surface and had time to form some small crystals. The third is fine-grained since it only has small crystals.) How does changing the cooling time change the rock? (The longer the cooling time of igneous rocks the larger the crystals.) What type of texture would they get if they changed the rate of cooling as the rock was forming? (Porphyritic – since it is a mixture of large and small crystals.) Is there a relationship between cooling time and size of crystals? (Yes.)

Step 7:  Setup of Next Day’s Activity

This is step one of tomorrow’s Introductory Activity. It will take a bit of time for the drops to evaporate. This is why it is set up the day before. Have each group in half the class write their initials and #1a on the edge of one microscope slide, and their initials and #3a on the edge of a second slide. Then they will put one drop of NaCl on the slide #1a and place it on the radiator without spilling it, and three drops of NaCl on the slide #3a and place it on the radiator without spilling it. Have each group in the other half of the class write their initials and #1b on the edge of a microscope slide, and their initials and #3b on the edge of a second slide. Then they will put one drop of CuSO4 on slide #1b and place it on the radiator without spilling it, and three drops of CuSO4 on the slide #3b and place it on the radiator without spilling it.
If you have time, ask students, “Where do we find igneous rocks?” (Let students discuss and tell them this is what they will discover tomorrow.)

Note to Teacher: #1a and #3a are slides with one and three drops of sodium chloride, #1b and #3b are slides with one and three drops of blue copper sulfate. The crystals in these solutions will show the same properties as the crystals in igneous rocks. The longer they take to form the larger they grow. When we have more drops it takes longer to form crystals.


Day 2

Step 1:  Set Up.

This was done the day before. See Step 7 above.

Step 2:

Have students pick up their microscope slides and look at them. Is there a difference between one drop of salt and three drops of salt? (The three drops of salt took longer to evaporate and thus should have bigger crystals.) Students may use a good magnifying glass to see any differences. This can be done under a microscope since the electric light of the microscope will dry the slide and students should be able to see crystals forming after five minutes.

Students may substitute the CuSO4 solution for the NaCl and place it on a microscope slide to watch crystals form. (A larger drop will take longer and may form bigger crystals.)

Step 3:

Pose the following problem for homework. You will be given a saturated solution of CuSO4. You will be shown how to tie a string to one crystal of copper sulfate and the other end of the string to the center of the pencil so that crystals will grow on the string. How could you set up a controlled experiment to test this hypothesis: If the copper sulfate evaporates slowly the crystals will be (larger/smaller.) You can place beakers anywhere they won’t be bothered.

Explain to your students that they will be watching a couple of video segments and they are to use their knowledge from yesterday to help them with the lesson.

Step 4:

Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to raise their hands when they can tell why the study of Igneous Rocks began in the 1780’s? START near the beginning of the video on the black and white portrait of James Hutton as the narrator says, “The study of Igneous Rocks began in the 1780’s.” PLAY the video until you hear the narrator say, “That the earth was once covered entirely with a great ocean from which all rocks formed, starting with granite. Hutton disagreed.” PAUSE the tape. Ask your students, “Why did Hutton disagree?” Accept any answer and ask them to continue watching to discover the answer. Could Hutton’s disagreeing have something to do with why the study of Igneous Rocks began in the 1780’s? (Hutton believed that the whole earth was not covered with water. What made Hutton say this?) Refocus your students.

Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to raise their hand when they can tell why the study of Igneous Rocks began in the 1780’s? They can also tell us why Hutton disagreed. RESUME PLAY and PAUSE when the narrator says, “He reasoned that the granite must have been injected into the strata as a molten liquid and not been precipitated from a primordial sea.” Ask students what type of rock is granite? (Intrusive igneous, from yesterday’s work.) Where does granite form? (Large-grained, deep within the earth) Why did Hutton disagree? (He saw what he believed to be an igneous rock or non-sedimentary rock between other layers of rock.) Why do we say the study of Igneous Rocks began in the 1780’s? (Most rocks were thought to be sedimentary.) (Pose these last two questions – don’t answer them.)

Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to check their answers to see if they are correct. Why do we say that the study of igneous rocks began in the 1780’s? RESUME PLAY and STOP when the narrator says, “Thanks to Hutton, geologists recognized a new class of rocks called Igneous, literally fire-formed rocks.” Ask students, “Why did Hutton disagree?” (Hutton saw a link between rocks formed at the surface and rocks formed at great depth like granite.) Why do we say the study of Igneous Rocks began in the 1780’s? (Due to Hutton seeing the link between the rocks forming at depth and the quickly forming deposits of volcanoes.) What was the connection between erupting volcanoes and granite? (Both are products of molten liquid or magma.)

Note to Teacher:
You will be stopping the video several times and refocusing the video each time with the same question. You are looking to cause the students to interact with each other and the video by trying to predict and answer the question with progressively more and more little bits of information.

Step 5:

FAST FORWARD the tape and START on the picture of the yellow crack on a black screen where the narrator says, “The ascent of magma is a process called intrusion.” Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to answer the following question, “What is the difference between intrusive (plutonic) and extrusive (volcanic) igneous rock?” PLAY the video and PAUSE when the narrator says, “If it erupts at the surface the igneous rock is called extrusive or volcanic.” Discuss. (Intrusive igneous rock forms underground, extrusive forms at the surface.)

Step 6:

Give every student a Student Sheet #2: Rocks. Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to only use their sense of hearing for the next segment. They are to answer the following question. What are mafic, felsic, and intermediate rocks? Then they use Student Sheet #2: Rocks and fill in the missing information.

YOU WILL RESUME PLAY OF THE VIDEO WITH THE SOUND ON AND COVER THE TV SCREEN. STOP on the picture saying Intermediate, after the narrator says, “These are known as the intermediate igneous rocks; diorite is one of the most abundant examples.“ Discuss. What are mafic, felsic, and intermediate rocks? Use the Student Sheet #2 Rocks to get the rest of the answers. (Mafic contains iron and magnesium and should be a darker colored high-density rock. Gabbro is an example. Felsic contains silicon and aluminum and should be a lighter colored, less dense rock. Granite is an example. Intermediate is a mixture of the other two, and andesite is an example.) What do you think these rocks look like? (Mafic is dark, felsic is a lighter color, and the intermediate is a combination of dark and light.) Note the dark and light minerals in diorite.) Discuss. REWIND AND REPLAY THE VIDEO CLIP with the picture to check the students’ predictions. The answers are above.

Step 7:

Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to tell how cooling time can be used to tell the difference between Plutonic and Volcanic Rocks. RESUME PLAY of the video and PAUSE when the narrator says, “And the more slowly the magma cools the larger the crystals will grow.” Discuss. (The longer the cooling time the larger the crystals. This is intrusive or plutonic rock. The smaller crystals have very little time to cool and are called intrusive or volcanic rocks.) REWIND, TURN DOWN THE SOUND, and look at the first two rocks in this segment. PAUSE and ask what is the difference? (The plutonic rock has larger crystals. Note: Both rocks are light colored felsic.) Why? (Plutonic cools slowly inside the earth while volcanic cools quickly.) FAST FORWARD to the next two rocks, PAUSE and ask what is the difference? (The plutonic rock has larger crystals. Note: Both rocks are dark colored mafic.) Why? (Plutonic cools slowly inside the earth while volcanic cools quickly.) FAST FORWARD to the next two rocks, PAUSE and ask what is the difference? (The plutonic rock has larger crystals. Note: Both rocks are dark and light colored intermediate.) Why? (Plutonic cools slowly inside the earth while volcanic cools quickly.) Turning the sound off causes the students to show you they understand the segment and reinforces the main point.

Step 8:

TURN DOWN THE SOUND BEFORE YOU PLAY THE NEXT SEGMENT. ASK A STUDENT TO SUPPLY THE NARRATION FOR THE LAST THREE SINGLE ROCKS. Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to look at the rock on the video and their notes (Student Sheets #1 & #2) and answer the following questions, “ Where did the rock form? Is the rock mafic or felsic? What type of minerals does the rock contain?” RESUME PLAY and PAUSE on the first rock. Ask one student to name the rock and tell it’s crystal size. (It is a glassy rock since it has no crystals - it is called obsidian.) Where did it form? (It formed very quickly, on the surface.) Is the rock mafic or felsic? (Felsic – note volcanic glass is clear so a small impurity could make the rock look darker. It is like looking through many sheets of smoked glass. This is a tricky one.) What type of minerals does it contain? (Silicon and aluminum – you can tell this by looking at Student Sheet #2 Rocks.) RESUME PLAY and PAUSE on the second rock. Ask one student to tell about the rock. Where did it form? (The rock formed quickly near the surface. Fine-grained – it is called rhyolite.) Is the rock mafic or felsic? (Felsic – a light colored rock.) What type of minerals does it contain? (Silicon and aluminum – you can tell this by looking at Student Sheet #2 Rocks.) RESUME PLAY and PAUSE on the third rock. Ask one student to tell about the rock. Where did it form? (It formed slowly below the surface since it is coarse-grained – it is called granite.) Is the rock mafic or felsic? (Felsic – a light colored rock.) What minerals does it contain? (Silicon and aluminum – you can tell this by looking at Student Sheet #2 Rocks.) The end of this segment is on the picture of the third rock where the narrator says, “…the more slowly the magma cools, the larger the crystals will grow.” Discuss. Note: It is not necessary to replay the last segment with the sound on since you used this segment to test students’ comprehension.

Step 9:

Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to use what they learned to solve a real life problem. This last segment is a real life problem that will be used to check your understanding of yesterday’s and today’s work. The first part of this clip is the introduction. It will show and explain how an igneous dyke intruded into the surrounding rock. The last part will be played without the sound and you will look at the picture and write on the bottom of Student Sheet #2 Rocks what is happening. PLAY the video and PAUSE when the scientist says, “…because crystal size is a good indicator of relative cooling rate.” (Don’t let it go further.) Now ask for a volunteer. TURN DOWN THE SOUND and ask students to write down what they believe happened on the bottom of Student Sheet #2 Rocks. RESUME PLAY and STOP at the end of the segment after the scientist points to the rock and says, “…center, where the crystals are somewhat larger.” REWIND TO THE PREVIOUS PAUSE POINT AND ASK ONE STUDENT TO SUPPLY THE NARRATION. OTHER STUDENTS MAY BE ASKED TO COMMENT ON WHAT THIS STUDENT SAYS. RESUME PLAY and STOP at the end of the segment after the scientist points to the rock, and after he says, “…center, where the crystals are somewhat larger.” Discuss. (The student’s narration should say, “The crystal size should be smaller at the edges of the dyke where it cooled more quickly and larger at the center of the dyke where the magma cooled more slowly.”) REWIND AND REPLAY THE VIDEO CLIP with the sound to check the students’ predictions. Note: You may choose to not rewind the segment two times depending on your students and how fast they pick it up.


Cross-Curricilar Extensions

#1: Classification of Rocks

Step 1:

Ask students to take out the set of rocks out of their basket. Ask students to make up criteria and group these rocks by a question they pose. A question like “Does the rock have ______.” Yes would be the group of rocks that show this characteristic, and no would be the group of rocks that don’t show this characteristic. There must be rocks in both groups. Use the bottom of Student Sheet #2 Rocks to come up with as many ways as you can to classify igneous rocks.

Step 2:


Go over the different ways they could have grouped the rocks. (Large or small crystal size, dark or light color of rock, how heavy or dense the rock is, if the rock has air bubbles, if it is a rock or mineral, etc., would all be ways to group them.) Note: all minerals are in italic. Have students take out the minerals Quartz, Feldspar, Biotite Mica (black). Now have them group the igneous rocks again. Go over the different ways they could have grouped the rocks. Talk about their effective use of questions. The alternate grouping methods now make more sense. This is why students must be exposed to minerals first. Did any one use the question, “Did the rocks have a grain size smaller than 1 mm?” (It is used to determine if the rock is fine- or coarse-grained.) Ask students how they would have grouped rocks if they had not performed the previous day’s activity.

Step 3:


Visit http://www.science.ubc.ca/~geol202/rock_cycle/igneousrx.html and introduce a classification key. Provide students with a FOCUS FOR MEDIA INTERACTION, asking them to use what they learned about crystal size and minerals to explain this key. (Rocks are grouped by mineral content and crystal size. This classification key is similar to Student Sheet #2: Rocks.) Note: this site could have been used before.


Alternate Activity: Aspirin or Benzoic Acid in Alcohol

Heat aspirin in rubbing alcohol. Crush tablets and add while stirring until the aspirin no longer dissolves. Pour the liquid into three containers. Caution: Alcohol is flammable and cannot be heated with an open flame. The teacher can do the preparation and students can see the results in a short period of time. Once you get all the aspirin to dissolve, put the solution in three containers: one at room temperature, one in ice water, and one in very warm water. You will see the crystals grow immediately rather than waiting a couple of weeks. This may be a teacher demonstration. You may use benzoic acid rather than aspirin. Ask students to explain how this is similar to the formation of igneous rocks. Pretend the crystals formed a rock that was mafic. Use Student Sheet #2: Rocks to determine the name of the rock.


Culminating Activity #2

Step 1:

Ask the students to create a controlled experiment with copper sulfate. They have saturated solutions of CuSO4 to test this out. Show students how to tie a string to one crystal of copper sulfate and the other end of the string to the center of the pencil. Make sure the string touches the bottom when the pencil is resting on the edge of the beaker. All groups have exactly the same set-up. How could they set up a controlled experiment to test this hypothesis: If the copper sulfate evaporates slowly the crystals will be (larger/smaller)? This can be done by two groups of students taking two beakers and placing the beakers in different places in the classroom (or school) for about two weeks so the beakers differ by one variable. The copper sulfate should be in a place where it will not be disturbed, but where the students have access. They will also place a thermometer with the beaker and record the time, temperature, amount of liquid left, and crystal size once a day for four weeks. (Radiators or windowsills may cause smaller crystals due to the rapid evaporation, while the back of an empty cabinet could take longer and form larger crystals. If the beaker is covered it may take longer to evaporate. An experiment could be done with a covered and uncovered beaker to see which takes longer to evaporate and thus form larger crystals.)

Step 2:

Collect the data for a couple of weeks. The solution may take a while to evaporate. Take data at the same time and have students create line graphs for the amount of water left vs. time and the size of the crystal vs. time. Determine the rate.

Step 3:

Were the students’ hypotheses proved or disproved? What could the students have done to make it better? Pretend the crystals formed a rock that was felsic. Use Student Sheet #2: Rocks to determine the name of the rock.

Step 4:

Devise an experiment to determine the cooling rate of igneous rocks by visiting your local volcano. (Possible answers - Go to your local volcano and after the rock cools sample a rock directly at the surface and a rock below the surface. Compare the size of the crystals.)


Culminating Activity #3: Watch Glass and the Snow



Step 1:

Take a can of snow spray (not the foamy, but the flat spray that is used to make fake snow on your windows). Ask students what will happen if we spray this into a watch glass? They are to write down their predictions and tell why they made their predictions. They are to take out a sheet of paper and draw the watch glass and then draw what they will predict will happen if we spray the snow into the center of the watch glass.

Step 2:

Each group will come up and spray the snow into the watch glass and watch it dry. The ventilation of this part is important. Students are to record and explain what they see. (Larger crystals in the center of the watch glass where the drying time is longer.) Note: students should wear safety goggles for the above and the room should be well ventilated.

Step 3:

Students are to look at the other activities they did and use these activities to explain what is happening. Ask students to summarize how igneous rocks are formed. Ask students how they can make this into a controlled experiment. (Spray the snow on a window or flat piece of glass.) Also spray the snow on a window – flat surface – and talk about why the watch glass produces different results. (The curved glass lets the snow dry faster where it is thinner and slower where it is thicker – this is harder to do with a flat surface.) Pretend the crystals formed a rock that was mafic. Use Student Sheet #2 Rocks to determine the name of the rock.


Cross-Curricilar Extensions

SOCIAL STUDIES/LANGUAGE ARTS
Assign students to a debate. How close to volcanoes can we farm? Have one group of students be in favor of farming – these students are from Hawaii. Have another group of students be opposed – these students were from Pompeii. Points to be covered. What advantage does farming near a volcano have?
Throughout history, man has deified forces of nature. What Volcanic Gods or Gods of the Earth did the early Hawaiians, Romans, or Greeks worship?

VISUAL ARTS
Which artists use igneous rocks for their sculptures? (Check Hawaii.)
Create a sculpture using igneous rock.
Visit the mineral display at the local museum or visit the American Indian art area and look at the arrowheads, and other uses of obsidian.

DRAMA
Assign a group of students to write and perform a play showing the formation of a crystal under different temperatures.

SOCIAL SCIENCE/EARTH SCIENCE
Volcanoes and Plate Boundaries
The Web site http://www.pbs.org/wgbh/aso/tryit/tectonics/ , a tie-in to the PBS series Nova, allows students to see the relationship between tectonic plates and volcano formation. Students can try four different types of plate motion and determine which is related to volcano formation. Requires Shockwave plug-in.
Research the Volcanic Island south of Greenland. This is a new volcanic island that had no life. Now life is appearing – this is called succession. How is succession occurring on this island?
Surgeons use scalpels with obsidian blades rather than stainless steel because obsidian retains its sharpness. Is this being done? (Yes.) What problem does this cause? Give advantages and disadvantages.

SCIENCE AND MATH
Research the following topic: How does the size of crystals tell you the rate at which magma cooled? Check the Hawaiian volcano observatories to see what information they have. What is the rate?


Community Connections

  • Visit your local college or university’s Web site and ask a geologist if they wouldn’t mind answering your students’ e-mail inquiries for a week.

  • Invite a local scientist in your community to talk about how they perform research.

  • Look at local buildings. Do any of them use igneous rock as a building stone? Do they use igneous rock as inside or outside decoration, countertops, flooring, gravels, barbeque stones, etc.?

  • Visit a local building supply store and see the type of stone they sell. Contact them to find out what types of igneous rocks are used the most. Then figure out why.