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Geologic Time Scale:

10 cm, calendar, clock

A 8th grade STEM lesson

Elena Tellechea

11/23/2023

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Notes for teachers

I had high hopes trying to squeeze in 3 models for geologic time. I had to cut out transferring extra events to the 10 cm ruler for my slower paced classes. Most students preferred the calendar model outlined in the article, so in the future I plan to spend more time developing that model. I also need to find a better way for students to glue in events on the clock model at the end of the lesson. I would also like to spend more time on using scientific notation. I initially was inspired to write this lesson because my students struggle to conceptualize geologic time and what millions of years looks like. When we get to the 8th grade standard on human consumption of limited resources such as fossil fuels, I have students who think we can recreate the necessary environments and just make more. This year, after doing this lesson, I did not get that response.

List of Materials

Google Slide presentation

link

Enough printed copies of the article for each student.

link

Enough printed guided notes worksheets for each student.

link

One full calendar year printed on several sheets of paper for each lab group, with each month large enough for students to mark events with post-its.
Post-its
Tape or glue sticks
Enough printed copies of a blank analog clock for each student.

see guided notes

5E Lesson Plan - STAR Program

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Standards

8.E1U1.6

Analyze and interpret data about the Earth’s geological column to communicate relative ages of rock layers and fossils.

Standards

8.EE.C.7

Fluently solve linear equations and inequalities in one variable.

a. Give examples of linear equations in one variable with one solution, infinitely many solutions, or no solution. Show which of these possibilities is the case by successively transforming the given equation into simpler forms, until an equivalent equation of the form x = a, a = a, or a = b results (where a and b are different numbers).

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Objective:

SWBAT construct an explanation for the purpose of the geologic time scale.

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Agenda (55 minutes)

Engage (8 min): 10 cm ruler represents 1 billion years. Label 1 million on the ruler. Probe: How old is Earth. Students choose from several possible answers.

Explore (15 min): Read article Understanding Geologic Time and complete guided notes together. Revisit probe and correct answer if wrong. Students label several Eras on ruler. Do not give them the correct answer yet. Fill in names for Eras on the Geologic Time Scale (guided notes). Pick 1 event from each Era to label on the ruler. (If you have time)

Explain (10 min): Ratios and Cross Multiply to solve for (x). Did we label the ruler correctly? This would also be a good opportunity to practice scientific notation (exponents). How many more rulers would we need to label 4.6 billion years? Compare time organized on ruler to Geologic Time Scale.

Extend (12 min): 4.6 Billion years in a calendar. Group work; students will use guided notes to label events.

Evaluate (10 min): 4.6 Billion years in one hour. Label same events but independently and in a blank analog clock.

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Intro/Driving Question/Opening

Students will record the learning objective in their Interactive Science Notebooks: I can construct an explanation for the purpose of the geologic time scale.

Students should be given a printed copy of a 10 cm ruler. The 10 cm ruler represents 1 billion years. Label 1 million years on the ruler.

Is 1 million years a big number? Is 1 million years a big number compared to 1 billion? How long have humans been here according to the Geologic Time Scale?

Probe: How old is Earth? Students are given several choices to choose from. Students will discover the answer after the Explore portion of the lesson.

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Hands-on Activity Instructions

The 10 cm ruler is completed together as part of student notes. Adding the math component emphasizes each Era on the Geologic Time Scale and it’s worth taking the time to work out the ratios to find each Era on the 10 cm ruler. My advanced math students get a little impatient but.
The calendar is everyone’s favorite because they get to work with the lab groups, which are organized into groups of 4. There is no consequence for making mistakes and we go over answers together on the board.
The clock is the most challenging because they are encouraged to work independently and they have to transfer what they’ve learned to a new framework for organizing time.

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Assessment

Students will organize geologic time on a 10 cm ruler during guided notes with teacher guidance.

Students will organize geologic time on a calendar with lab groups.

Students will organize geologic time on an analog clock independently.

Note: Same events will be used each time, just a different framework for organizing events.

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Differentiation

Guided notes will be presented on the Promethean Board and completed with students, highlighting key words.

Math will be modeled and broken down into simplest steps. The ruler will be presented with the math problems and labeled as math problems are completed so that students can see the connection and correct mistakes.

A class calendar will be presented so that groups can correct mistakes. Cooperative learning for completing the calendar model.

Remediation

Extension/Enrichment

Students will be given opportunity to complete math component on promethean board.

One student from each group will be selected to label extra event on class calendar.