Relative and absolute dating activity




Learning Goals

Context for Use

Students will have a more in-depth understanding of what radioactive decay is. Students will understand how scientists use half-lives to date the age of rocks. This activity can be adapted for older students, but is used in an 8th grade earth science classroom. Class size can vary, but activity should be done in groups of Students should have the skill to set up a data table and a graph, however, if you want to use this activity with students that have not, you can provide them a template with that information.

As far as mastery of content, this activity is done in our rocks and minerals unit. Students should have some prior knowledge of rocks and how they are dated. This activity would also be easy to adapt when talking about half-lives within a chemistry course. New information needed to be introduced with parent and daughter isotopes. Once students are in their groups, with supplies, and general directions are given, they are on their own for doing their runs.

They will do this 8 times. Once they are finished with their 8 runs, they will record their data on the class data table which can be on the board. Once all groups data is on the table, you can calculate the average for each run and determine a class average. Students should recognize each time the number should go down by appx half.

Then students take the class data and create a graph comparing the number of parent isotopes to the number of half-lives.

Radioactive Dating: Looking at Half-Lives Using M&Ms

Once this is done, students have some post questions they are given that they should record in their science notebook. The first post question caused some confusion: Why didn't each group get the same results? A lot of the students said because they shook the containers differently This was a new activity we implemented last tear. Radioactive decay and half-lives can be a very difficult concept for our 8th graders to grasp. Place a number beside each event according to which happened longest ago 1 and which happened most recently 10 c.

Rewrite the list in reverse chronological order, with the most recent at the top and the most long ago at the bottom d. To the new list, add information about exactly how many years ago the event occurred 4. The list so far is what geologists refer to as a relative or sequential timeline. Discuss the difference between relative time, ordering events by which happened first, and absolute time, the number of years ago each event happened.

Radioactive Dating: Looking at Half-Lives Using M&Ms

A relative timeline can be observed from rock layers just by reading it from bottom to top. But is it possible to observe the actual, absolute number of years ago a rock layer formed just by looking at it? You can determine absolute time for events from your own life because you can remember each event, but nobody can remember the exact, absolute age of a rock. Scientists use special tools to find the absolute, number of years ago a given rock layer was formed. More on this in later lessons. After the discussion about relative and absolute time, students can categorize events into a hierarchical series of time periods.

These will form the largest divisions of your personal time scale and will be called eons.

Students should draw a horizontal line across the eon, era and period columns, dividing their table according to the criteria they chose. They should name the categories with a 1 word label that ends in the suffix —ian or —ic.

WHO'S ON FIRST? RELATIVE DATING (Student Activity)

In the eon column, they should write down the names they chose. Now students should divide each of the eons into 2 or 3 eras based on a different criteria. Students should divide their tables by drawing a line across the era and period columns according to the criteria they chose and should write in the name of the eras. Finally, students should divide each era into 2 or 3 periods, if that is possible. Students should divide their tables by drawing a line across the period column and should write in the name of the period.

If you have remaining time, students can color their tables or share them with one another in small groups. Sources Activity adapted from http: Here you can find detailed information about each eon, era, period and epoch in Earth History.

My Time Scale: Introduction to Relative and Absolute Dating Activity

Furthermore, you can learn about how the geologic time scale was created and how it is organized. In your notebook, list at least 10 of the most important events of your lifetime. Use these events as your first 4 on your list: Arrange these events in order by placing a 1 in front of the event that occurred first and a number 2 for the event that occurred second, etc.

In the LAST column, write these events in order from most recent to longest time ago.

Write your entries using decimals. Wait for further instructions. If you have extra time, add more events to your time scale! Fold this flap back using the line below as a guide. Volk- Understanding geological time. Fossils and Geologic Time.

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relative and absolute dating activity Relative and absolute dating activity
relative and absolute dating activity Relative and absolute dating activity
relative and absolute dating activity Relative and absolute dating activity
relative and absolute dating activity Relative and absolute dating activity
relative and absolute dating activity Relative and absolute dating activity
relative and absolute dating activity Relative and absolute dating activity
relative and absolute dating activity Relative and absolute dating activity

Related relative and absolute dating activity



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