Goal(s): Students will develop an understanding of how sedimentary rocks are formed.
Grade level(s): 4-5
Students will be able to identify a sedimentary rock by its visual markings (lines/layers).
Students will be able to explain how sedimentary rocks are formed (through erosion and the compressing/cementing of smaller rocks and plant/animal material).
Time Allotment: 1 class period
What root word in “sedimentary” tells you how sedimentary rocks are formed?
What visual characteristic helps us identify sedimentary rocks?
Why do sedimentary rocks have layers?
Material(s): (all materials are needed for each pair of students)
pint-sized milk cartons (three per pair)
Vocabulary: sediment, sedimentary rock, cement, compressed/compression, sandstone, coal, and limestone
Anticipatory Set: Students will be told the objective. The students will be given a sedimentary rock and asked to observe the rock and record their findings in their science journal. The students will be asked to recall the previous lesson on weathering. Students will be asked why they think their rock appears to have different layers. Answers will be written on the board.
Direct Instruction/Guided Practice: The focusing questions will guide the class in a discussion about sedimentary rocks. Vocabulary paired with pictures will be introduced. Answers to the questions will be solidified through the viewing of an interactive video on how sedimentary rocks are formed (http://videos.howstuffworks.com/hsw/23899-the-geology-of-earth-igneous-rocks-video.htm). Students will then be told that they are going to make three different models that represent a sedimentary rock-sandstone, coal and limestone (visuals will be shown). Uses for each will be given. Students will be asked how they think each of the rocks are formed based on their names. They should recognize that each is formed by different layers of sediment. Next, demonstrate how each will be made using the materials provided at each station.
Independent Practice: Students will be told to find their science buddies and to go to a station set up with materials. Each pair of students will follow the written recipe to make models of sandstone, coal and limestone. If wait time is needed for each of the models to dry, students will be given a packet to read to gather more information on various kinds of sedimentary rocks. Document provided by www.nps.gov titled Geology Student Field Guide and Scavenger Hunt.
Once the models are dry, students will investigate their sedimentary rock models and record their observations/comparisons in their science journals. Recordings should include a drawing with labels to identify the visual markings of a sedimentary rock and a brief summary to show their understanding of how sedimentary rocks are formed.
Closure: Students will gather as a whole group with their science journals to discuss their findings. Students will be told that they have just produced models that represent how sedimentary rocks are formed. The focusing questions will lead the class in group discussion of the experiment. The students will be asked:
- What attributes did your rocks have in common? Why?
- How did the three piles of rocks differ? Why?
- What natural materials make up sandstone? Coal? Limestone?
- How did our experiment show what happens to rocks/stones, plants, and animal materials through the erosion process?
Assessment: Students will be assessed according to their participation in the experiment and the group discussions. Students will be assessed according to their ability to:
Identify a sedimentary rock by its visual markings (lines/layers).
Explain how sedimentary rocks are formed (through erosion and the compressing/cementing of smaller rocks and plant/animal material).
Accommodations: To accommodate ELL's, auditory, and visual learners, each pair of students will be given written instruction paired with pictures as well as verbal instruction by an adult in order to complete the activity. An alternative assessment may be given in the form of an adapted worksheet in which students are given a partial drawing and a fill-in the blank text. Students may also verbally explain the process using a model with rocks, clay, and water.
1) Students could produce written riddles (based on their knowledge of sedimentary rocks) for each rock they made and invite another class to come in and figure out which is which.
2) Creative writing assignment-students could write a narrative for one of the models that explains how the rock was formed.
Directions for rock models: Have materials set up at individual stations with written directions and a completed example for students to follow.
a) In a milk carton (with top cut off), mix 3 teaspoons of cement with wet sand.
b) Allow to dry.
c) Remove from carton to reveal the sandstone.
a) In a milk carton (with top cut off), mix 3 teaspoons of cement with wet mud and decomposed leaves.
b) Allow to dry.
c) Remove from carton to reveal the coal.
a) In a milk carton (with top cut off), mix 3 tablespoons of plaster with equal parts water.
b) Allow to dry.
c) Remove from carton to reveal the limestone.
Sedimentary recipes adopted from http://www.coaleducation.org/lessons/sme/elem/7.htm