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Time Travelers: Measuring the Age of the Earth Lesson Overview

Students will measure the mass of several objects which will represent “fossils.” Each object’s mass will represent a specific age of the object. Students will gain an understanding of how scientists use absolute dating to accurately determine the age of objects and how relative dating is used to generally determine the age of objects.


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60-70 Minutes
2-4 Students
PTI Inquiry
2.5, 2.6, 3.1, 3.5, 4.2, 4.4, 5.2, 5.3, 5.7, 5.8, 6.1, 6.2, 7.1, 7.2 , 7.3, 7.5
Lesson Components Time Inquiry Skills Tech. Used Engage Level Brief Description
Engage 5-10 min   Computer, Projector 3 Students will watch the intro time lapse video to understand how substances deteriorate as they rot.
Explore 20 min 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7 Baggies, rice, electronic scales 3 Using the connection to the video clip, students will mass baggies with various amounts of rice to model material decomposition. Students will use this data to develop an idea of the object’s age.
Explain 10 min 4.2, 5.2, 5.3, 7.1, 7.2 Classroom and Individual Student Timelines 2 Students will use their data to formulate a claim about which baggie would be considered “oldest” based on its amount of matter. Students will use a chart to provide evidence and justification for their claim. Students will share their group data to develop a class-wide timeline. Using the data, students have an understanding of the object’s age.
Expand 10 min 5.7, 6.1, 6.2, 7.1, 7.2 none 3 Students will utilize the class-wide timeline to determine the relative age of “unknown” objects through the use of evidence and the Law of Superposition.
Evaluate 15 min 4.2, 5.7, 7.3 none (Computer optional) 2 Students will utilize the group and class-wide timeline to define the 2 ways scientists can determine the age of an unknown object. Students will also be able to predict the accuracy of the methods of dating.

Level of Student Engagement
1     Low     Listen to lecture, observe the teacher, individual reading, teacher demonstration, teacher-centered instruction
2     Medium     Raise questions, lecture with discussion, record data, make predictions, technology interaction with assistance
3     High     Hands-on activity or inquiry; critique others, draw conclusions, make connections, problem-solve, student-centered

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