CHANGES OVER TIME

CHANGES OVER TIME

MASTER TEACHER Cheryl T. Gillenwater

GRADES 4 – 6

OVERVIEW
In this lesson the students will determine that certain past events affect present and future events. They will identify and observe effects of events that require time for changes to be noticeable including growth, erosion, dissolving, weathering, and flow. (TEK 4.10A, 5.11A) The students will also be able to draw conclusions about “what happened before” using fossils or charts and tables. (TEK 4.10B, 5.11B)

ETV SERIES
3-2-1- Classroom Contact - #115 Earth Is Change – Erosion
Natural Phenomena - #105 Trees: The Biggest and Oldest Living Things
3-2-1- Classroom Contact - #114 Remains To Be Seen - Fossils

LEARNING OBJECTIVES
Students will be able to:
* identify and observe the history of growth in trees based on tree rings.
* identify and observe the effects of erosion, dissolving, and weathering on the Earth.
* identify and observe the effects of erosion formed by water and wind.
* draw conclusions about changes in the Earth from knowledge of fossils.

MATERIALS
#1 Water Carved This
(per each group of 4 to 5 students)
1 large plastic or aluminum type pan (approximately 6” deep, 13” wide, and 20” long)
1 - 10 pound bag of sand (available from the Curriculum and Materials Center)
1 - 20 to 24 ounce plastic cup with small holes perforated in the bottom in a circular fashion (available from the Curriculum and Materials Center)
paper towels

#2 Effects of Acid Rain (Chemical Weathering)
(per group of 3 to 4 students)
1 piece of chalk
1 eye dropper
1 container (butter dish, aluminum pie pan, glass jar, etc.)
approximately ½ ounce of vinegar
1 sheet of extra fine of fine grade sand paper

#3 Wind Erosion
(per group of 3 to 4 students or may be used as teacher demonstration)
1 box with top and one side removed
1 bag of sand (available from the Curriculum and Materials Center)

#4 Glacier Erosion
(per group of 3 to 4 students)
1 plastic tray or aluminum roasting pan
soil that includes pebbles and leaves or twigs – approximately 3 inches deep
ice cube (any item that will represent a glacier such as a piece of wood will work)

#5 Temperature Erosion
(teacher demonstration)
1 sterno or other heat source
1 stand for sterno to go under
1 Pyrex beaker
several marbles
1 Pyrex container filled with water and ice (mostly ice)

#6 Tree Rings As Records of the Past
(per group of 3 to 4 students)
3 to 4 hand lenses
sections from a recently cut tree
local precipitation records for the period of the life of the tree (annual rainfall totals)

#7 It’s A Fossil!
(per student)
6 ounces of plaster of paris
1 seashell, leaf, bone, macaroni, nut or any other object that would make a suitable fossil
1 nine-ounce plastic or paper cup

VOCABULARY
erosion: the wearing away of the surface of the earth, a continual process, picking up and carrying away pieces of rock
weathering: gradual physical and chemical wearing away of rocks, weathering is the breaking down of the materials of Earth’s crust into smaller pieces
deposition: the dropping off of bits of eroded rock.
glaciers: large sheets of ice.
annual rings (growth rings): the rings of growth on a tree that marks a year of growth
climate change: changes in climate over time, one area of global change
core sample: piece of a tree, about the size of a drinking straw, pulled out by an increment borer
cross section: a horizontal slice of a tree used to age the rings
dendrochronology: the science of dating events and environmental changes by studying growth rings in trees and aged wood
dendrochronologist: a person who studies tree ring growth
increment borer: an instrument used to take a core sample from a tree
fossils: any part of a once-living organism that is now preserved in earth’s rocks, found most often in sedimentary rock
mold fossil: imprint made by the outside of a dead plant or animal, a mold forms when water slowly wash the animal or plant remains out of the rock
cast fossil: formed when a mold fossil is filled with sediments or minerals, the cast has the same outside shape as the original living thing
petrified: when minerals slowly take the place of the original, once living material, petrified means “stone”

DAY ONE
PRE-VIEWING ACTIVITIES
Display pictures of the Grand Canyon, tree ring section, and fossils. Ask the students if they know what all of these things has in common. As a whole class, students will brainstorm what they know about the Grand Canyon, tree ring section, and fossils. Record their responses on a KWL chart. Under column K list what the students know. Under column W list what the students want to know. Leave column L (for what they will learn) blank at this time. You will return to this column at the end of the lesson and fill in what the students have learned.

FOCUS FOR VIEWING (Earth is Change – Erosion)
To give students a specific responsibility while viewing say, “While you are viewing the video, look for the answers to question #1 on Activity Worksheet #1. Identify the kinds of forces that change the Earth quickly.”

VIEWING ACTIVITIES
Begin the video 3-2-1- Classroom Contact #115 Earth Is Change – Erosion when the screen shows the title Earth is Change - Erosion. Pause when the video shows three people walking in debris (no sound). At this time discuss the answer to question #1 on Activity Worksheet #1, What kind of forces change the earth quickly? (volcanoes, avalanches, earthquakes, mudslides, floods, and people). Focus the students by telling them to pay close attention because they will use the upcoming information to answer question #2. Resume the video. Pause the video after the hairdryer has blown a deep valley into the soil (no sound). Discuss what type of changes over time wind can cause. (forms valleys and hills) Focus the students by asking, “Try to imagine in your mind how many different changes a section of earth the size of Corpus Christi will go through over the course of one million years?” Resume the video. Pause when the video shows an animated man sitting on a hill with a stopwatch in his hand (no sound). Discuss the answer to question #3. (towns turn into cities, floods from ocean water, ocean water draws back and mountains begin to form and frost again, ice age returns, glaciers melt, river carves valley, earth pushes up new mountains, and forces push continents apart). Focus students by asking them to look for the answer to question #4, “What type of changes over time can water make on earth?” Resume video. Pause when the video shows a deep canyon formed in the streambed (no sound). Discuss and answer question #4. (carving out a river bed, water eroding the earth and carrying away soil downstream) Focus students by asking, “What other forces will cause changes over time?” Resume video. Pause video when screen shows landslide in canyon (no sound). Discuss and answer question #5. (plants loosen dirt and rocks, animals burrowed tunnels, and landslides) Focus students by asking them, “What formed the Grand Canyon?” (#6) Tell them to look for the answers to questions # 6 – 10. Resume video. Pause video when female student enters the helicopter (no sound). Discuss and answer questions # 6 – 10. (#6 – wind and water erosion; #7 – width – 10 miles at widest point, depth – 1 vertical mile above river; #8 – river; #9 – erosion from wind and rain (water) carrying rocks and mud into Colorado River; #10 – 2 – 6 million years old). Focus the students by asking them to look for the answers to questions # 11 and # 12. Resume video and run until the end. Stop video. Discuss and answer questions # 11 and # 12. (#11 – covered 7 different times by ocean and one time it was a desert; #12 – from soil that has eroded from the sides of the canyon and earth that the river force has dredged from the bottom of the river)

POST-VIEWING ACTIVITIES
Say, “Now that we have finished viewing information on erosion, you are ready to perform the Water Carved This experiment. The students will perform the experiment in cooperative groups. The directions are at the end of the lesson. The students should now understand that wind and water cause erosion that forms hills, valleys, and canyons.

DAY TWO
FOCUS FOR VIEWING (Trees: The Biggest and Oldest Living Things)
Display pictures of a sequoia, redwood, and/or bristlecone pine tree. Pictures of any tree will be sufficient. Show a picture of a cross-section of a tree and/or a piece of lumber that has growth rings. Asked the students, “Do you know what trees and tree rings can tell us about the past?” Tell the students that this video will show how important tree rings are to scientists in discovering information about the past. To give the students a specific responsibility while viewing say, “While you are viewing the video, look for the answers to question #1 on Activity Worksheet #2. What do trees provide?”

VIEWING ACTIVITIES
Begin the video when the screen shows the title Natural Phenomena – Trees: The Biggest and Oldest Living Things. Pause when the screen shows the formula for photosynthesis and a bird is heard chirping. At this time discuss the answer to question #1 on Activity Worksheet #2, What do trees provide? (tree roots hold soil and help slow erosion, dead trees release nutrients into the soil, trees provide people and animals with food, shelter, and oxygen) Focus the students by asking them to listen and watch for the answers to questions #2 and #3 on Activity Worksheet #2. Question #2 – What is the world’s largest tree according to shear volume of wood? Question #3 – What is the world’s tallest tree? Resume video. Pause video when screen is showing a span of the trees from the top to the bottom and the birds are chirping. Discuss and answer questions #2 (sequoia) and #3 (redwood) on Activity Worksheet #2. Fast forward video until screen shows cross section of log with Swedish boring tool on top (no sound). Focus students by asking them question #4, Define growth ring. Resume video. Pause video when the screen shows a cross-section of a tree (no sound). Discuss question #4 (one ring contains both light and dark wood, the light wood is from the early or spring growing season, and the dark wood is from the late or winter growing season, this combination represents one year of growth) and record answer. Focus the students by asking them question #5, What is the worlds' oldest living tree and how old is it? Resume video. Pause the video when the screen shows a Bristlecone Pine (no sound). Discuss and answer question #5. (Bristlecone Pine, 4,700 years old) Focus the students by asking them how scientist would date a tree when they do not know how old it is? #6. Resume video. Pause video when screen shows a cross-section of a Bristlecone Pine and music is playing. Discuss and answer question #6. (cross-dating – scientist use known tree ring dates and compare them to unknown tree ring dates and match the years, based on climate) Focus students by asking them to listen for all of the things that tree growth rings tell us? Resume video and play until end. Eject video. Discuss and answer question #7. (trees age, climate – wide ring normal to above normal precipitation, narrow ring – drought or low precipitation; date existence of lives of earlier people, when and how often forest fires occur, calibrate other dating methods of science, shows weather patterns of past and help us understand how the changes we are making today in climate will effect the future, knowledge of the past).

POST-VIEWING ACTIVITIES
Say, “Now that we have finished viewing information on tree rings, you are ready to explore tree rings first hand.” The students will then complete Activity #6, Tree Rings as Records of the Past. This activity will be done in cooperative groups. The directions are at the end of the lesson. The students should now understand the importance of tree rings as evidence of changes over time.

DAY THREE
FOCUS FOR VIEWING (Remains To Be Seen-Fossils)
To give students a specific responsibility while viewing say, “While you are viewing the video, look for the answers to question #1, on Activity Worksheet #3. What are fossils?”

VIEWING ACTIVITIES –
Begin the video 3-2-1- Classroom Contact - #114 – Remains To Be Seen – Fossils when the screen shows the title Remains To Be Seen - Fossils. Pause the video when the little girl is walking away with the fossil and you hear the sound of footsteps. Discuss and answer question #1 on Activity Worksheet #3, What are fossils? (Fossils are any trace of life from the past. Fossils can be traces of plants and animals that lived millions of years ago. Fossils may be tracks of an animal or bones which became buried in the mud.) Focus the students by asking them, “How do you think fossils are made?” Tell the students that there are three different methods by which fossils are formed and they will need to know this information to answer question #2 on Activity Worksheet #3. Resume the video. Pause the video when the female student says, “I’ll be back.” and the screen shows her standing by the footprints she made. Discuss the answer to question #2 on Activity Worksheet #3. (a. Something like seashells are covered by mud and turn into rock after a million or so years; b. example: trilobite – an animal is buried in the mud and after a long time it disintegrates leaving a hole shaped like the animal, minerals filled up the hole where the animal used to be and hardened and now you have a mineral animal instead of the real animal; c. footprints were made into mud or soft earth where an animal walked that then hardened into rock.) Focus the students by asking them to pay close attention to how archaeologist perform their work. Resume the video. Pause the video when “Remains To Be Seen” comes on the screen and the music is playing. Discuss the answer to question #3. How do archaeologists discover what life was like millions of years ago? (They find pieces of fossils and put the pieces of fossils together like a puzzle.) Resume the video and play until the end. Stop video.

POST-VIEWING ACTIVITIES
Say, “Now that we have finished viewing information on how fossils are formed, we are going to make our own fossils!” The students will work in cooperative groups and make their own fossil using the instructions from It’s A Fossil. The directions are at the end of the lesson. The students should now understand the three methods in which fossils are formed. Complete the L part of the KWL chart on what the students learned.

ACTION PLAN
Have a geologist or archaeologists speak to your class. Take a field trip to the Corpus Christi Museum of Natural History and Science. Plan activities that incorporate the rock and mineral, fossil, seashell, and tree ring displays at the museum.

EXTENSIONS
Social Studies – Have the students locate the Grand Canyon on a map and research its creation. Research the Sahara and Kalahari Deserts in Africa, the Gobi in China, and the Patagonia in Argentina. Locate these deserts on a map. Research the Dust Bowl in Oklahoma in the 1930’s. Find pictures of the Hubbard Glacier in Alaska and the Matterhorn in Switzerland. Research the geographical anomaly produced by glaciers.
Study the Native Americans with special attention paid to the Anasazi cliff dwellers that inhabited areas of Grand Canyon National Park. Have the students learn how the Anasazi used the canyon to their advantage. Research the theories on why they disappeared. Locate the Great Lakes on a map and research the formation of the lakes through glaciers.
Reading – Karen Hesse, Out of the Dust, (1997). The tragedy of the Dust Bowl is experienced through the eyes of Billie Jo, an adolescent living in Oklahoma in the 1930’s.
Writing – Create a brochure that will entice visitors to the Grand Canyon. Include a section on the formation of the canyon and the Native American Anasazi cliff dwellers and other Native Americans of the region, including the Havasupai.

Internet Connections –

www.conservation.state.mo.us
Tree Rings - This Internet connection provides an in-depth explanation of the formation of tree rings. The site provides good background information for the teacher.

www.soundport.com
Formation of A Canyon - This Internet connection provides the background information of Zion Canyon (a smaller canyon in the Colorado Plateau with the Grand Canyon). A complete lesson with activities and assessments are offered.

http://kaibab.org/geology/canform.htm
Grand Canyon Explorer – This Internet connection is an in-depth look at the formation of the Grand Canyon. It offers an easy to read detailed account of the formation of each layer of the canyon and what can be found there such as fossils. This site offers a large variety of pictures and maps showing all of the layers of the canyon and simulations of plate tectonics and continental drift. This is an excellent site.

Activity Worksheet #1 Causes of Erosion

1. What kind of forces changes the earth quickly?

2. What type of changes over time can wind cause?

3. In one billion years the Earth experiences many changes that occur in one area.
List some of the changes that can occur during one billion years.

4. What type of changes over time can the force of water make on Earth?

5. What other forces will cause change over time?

6. What changes over time formed the Grand Canyon?

7. How deep and wide is the Grand Canyon?

8. What force formed the depth of the Grand Canyon?

9. What forced formed the width of the Grand Canyon?

10. How old is the Colorado River?

11. What covered the land before the Grand Canyon was formed?

12. Why is the Colorado River muddy?

Activity Worksheet#2

How Trees Bring Us Knowledge of the Past

1. What do trees provide?

2. What is the world’s largest tree according to shear volume of wood?

3. What is the world’s tallest tree?

4. Define Growth Ring.

5. What is the world’s oldest living tree and how old is it?

6. What is cross dating?

7. What do the growth rings on a tree tell us?

Activity Worksheet #3 How Fossils Are Formed

1. What are fossils?

2. Name three ways that fossils are formed.

3. How do archaeologists discover what life was like millions of years ago?

ACTIVITIES

#1 Water Carved This
Materials:
(for each group of 4 to 5 students)
1 large plastic or aluminum type pan (approximately 6” deep, 13” wide, and 20 “ long)
1 5 pound bag of sand (available from the Curriculum and Materials Center)
1 - 20 or 24 ounce plastic cup with small holes perforated in the bottom in a circular
fashion (available from the Curriculum and Materials Center)
paper towels
Procedure:
1. Place sand in container and smooth until level.
2. Raise one end of the container with sand approximately 3 or more inches higher
than opposite end.
3. Hold cup with perforated bottom over higher end of sand and fill with water.
4. Observe and record changes that occurred as water eroded the sand and
formed rivers and valleys.
5. Use paper towels to absorb water at lower end of container.
6. Reshape sand forming mountains or dams.
7. Hold refilled cup of water over higher end of sand and observe and record
changes that occur when mountains and dams divert the water.
8. Compare and contrast the results of erosion from the first and second trials.

#2 Effects of Acid Rain (Chemical Weathering)
Materials:
(per group of 3 to 4 students)
1 piece of chalk
1 eye dropper
1 container (butter dish, aluminum pie pan, glass jar, etc.)
approximately ½ ounce of vinegar
1 sheet of fine or extra fine grade sandpaper
Procedure:
1. Lightly sand the chalk on two sides to removing the coating and flatten so the
chalk will lay flat.
2. Place the chalk into a container.
3. Slowly add drops of vinegar using the eyedropper.
4. Record your observations. (fizzing, hole is slowly forming)
5. Discuss why you think such a reaction occurred.
The vinegar and chalk represent the effects of acid rain on buildings and monuments. This is an example of chemical weathering that occurs everyday on Earth. If available the teacher may demonstrate this same effect using a piece of limestone and diluted hydrochloric acid.

Acid Rain Data Sheet

1. Define chemical erosion.
2. Predict what happens when chemical erosion from such things as acid
rain falls onto our monuments and buildings.
3. State recorded observations from the activity.
4. Write a hypothesis on chemical weathering/acid rain.

#3 Wind Erosion
Materials:
(per group of 3 to 4 students or may be used as teacher demonstration)
1 box with top and one side removed
1 bag of sand (available from the Curriculum and Materials Center)
Procedure:
1. Pile sand into middle of box.
2. Have students blow lightly over the sand from the open side of the box.
(The teacher may prefer to use a hairdryer to demonstrate this activity.)
3. Students will record their results.
4. Students will then reform their sand piles and will be given a choice of
materials to choose from to try and prevent the sand from moving.
(materials – water, plastic chips, pebbles, coins)
5. Students will blow on the sand and record their observations.

Wind Erosion Data Sheet

1. Define wind erosion.
2. Predict what will happen in this activity.
3. Write a hypothesis about wind erosion.
4. What happened to the sand as you blew on it the first time?
5. If you blew on it long enough, could you make the whole pile move?
6. What materials did you add to the reformed pile and why?
7. What was the effect after these materials were added and you blew on the
reformed pile?

#4 Glacier Erosion
Materials:
(per group of 3 to 4 students)
1 plastic tray or aluminum roasting pan (approximately 6” deep, 13” wide, and 20” long)
soil that includes pebbles and leaves or twigs – approximately 3 inches deep
ice cube (any item that will represent a glacier such as a piece of wood will work)
Procedure:
1. Place the soil in the container.
2. Slightly depress the ice cube or other item into the soil.
3. Slowly push the ice cube forward along the soil making a trench or valley.
This will simulate a glacier moving in mountain ranges. The results should be the formation of valleys and trenches. The soil that is being pushed out of the way should be piling up on the sides of and in front of the ice cube showing how other glacial features are formed. Have the students hypothesize that the trench or valley may eventually turn into a river or stream when filled with water from glacial or snow melting. Inform the students that the Great Lakes of the United States were formed from glaciers. The weight of the glaciers depressed the land and formed the lakes and the melting of the glaciers filled the lakes with water. It was estimated that the lakes were formed from approximately 40 million cubic kilometers of ice.

#5 Temperature Erosion
Materials:
(teacher demonstration)
1 sterno or other heat source
1 stand for sterno to go under
1 Pyrex beaker
several marbles
1 Pyrex container filled with water and ice (mostly ice)
Procedures:
1. Light the sterno and place the stand over it.
2. Place the Pyrex beaker containing the marbles on top of the stand.
3. Heat the Pyrex container and marbles for 5 minutes.
4. Place the heated marbles into the container with the water and ice.

Temperature Erosion Data Sheet

1. What happened to the marbles?
2. What do you think caused the marbles to crack?
3. Give examples of temperature erosion.
4. How can erosion due to temperature be prevented?
Take a walk outside and observe the sidewalk noting the cracks perhaps due to temperature erosion. Draw the students’ attention to the grooves in the sidewalk to help prevent temperature erosion. Refer back to the Oklahoma Dust Bowl as an example of temperature erosion from extended hot, dry, and windy conditions.

#6 Tree Rings As Records of the Past
Materials:
(per group of 3 to 4 students)
3 to 4 hand lenses
sections from a recently cut tree
local precipitation records for the period of the life of the tree (annual rainfall totals)
Procedure:
1. Using hand lenses the students will observe and describe the differences
between early and late wood.
2. The students will determine the actual age of the tree by counting the rings.
3. Using a modified t-chart, have one column for year, one for rainfall, and
one for width of tree ring. Record all information on modified chart.
4. Compare the annual precipitation records to the tree rings and observe and
record years of drought or normal rainfall.
5. Graph the width of the tree rings in mm using a line graph with a x and y-axis.
6. Graph the annual precipitation records in a bar graph with a x and y-axis.

Tree Ring Data Sheet

1. Which years had the best growth?
2. Predict why you think those years were the best.
3. Which years had the least growth?
4. Predict why you think those years were the worst.

#7 It’s A Fossil!
Materials:
(per student)
6 ounces of plaster of paris
1 seashell, leaf, bone, macaroni, nut or any other object that would make a suitable
fossil
1 nine-ounce plastic or paper cup
Procedure:
1. Mix plaster of paris according to directions on package.
2. Place approximately 6 ounces of mixture into the cup.
3. Have students place object on top of mixture and depress lightly.
4. After mixture begins to solidify remove object.
5. Allow mixture to fully dry and harden. (overnight)
6. Remove from cup.

Teacher Information Grand Canyon
A number of processes combined to create the Grand Canyon. The most powerful force was erosion, primarily by water (and ice) and secondly by wind. Other forces that contributed to the formation are the Colorado River, volcanism, and continental drift (plate tectonics). The Canyon is located in a desert, which is one of the main reasons why water has such a big impact. The soil in the Grand Canyon is baked by the sun and becomes very hard and cannot absorb water when the rains come. When it does rain the water tends to come down in torrents, which increases the erosional effects. The plants that grow in the Canyon tend to have very shallow root systems which allows them to grab as much water as possible when the rains come, unfortunately these root systems do nothing to deter erosion by not holding the soil in place. With a downpour of water, and nothing to hold it in place, soil can only go down to the Colorado River washing rock with it. This results in frequent flash floods roaring down a side canyon that can move boulders the size of automobiles, buses and even small houses.
Ice is the next main erosional factor. In the colder months, water seeps into cracks between the rocks, freezes, expands and pushes the rocks apart and widens the cracks. Eventually rocks near the rim are pushed off the edge and fall into the canyon. These rocks sometimes hit other rocks and are stopped, but on occasion one will cause a cascading effect and create a rock fall that drastically alters the landscape of the canyon.

Tree Rings
Trees grow in diameter by producing new wood in the layer just beneath their bark. A ring containing both light and dark wood represents a year’s growth. The first part of the growing season (early wood) is generally lighter in color. The denser wood is produced as the season comes to an end (late wood). Growth rate depends largely on precipitation or drought during the growing season. The widths of tree rings can be used to reconstruct rainfall and drought patterns of the past. Trees grow faster when they are young and this should be taken into account when interpreting ring widths. Dendrochonologists use a special auger (increment borer) to extract a slender core for study and tree ring analysis. This boring method does not harm the tree.

Updated: April 01, 2008