# Radiometric dating activity high school

This lesson will help students understand how scientists use carbon dating to try to The second lesson, Radioactive Decay: A Sweet Simulation of Half-life. This hands-on activity is a simulation of some of the radiometric dating information on radioactive half-life and carbon dating for more details on these subjects. Lesson Plan. Objective High School. Investigation and Absolute Age Dating – the age of the rock as measured by determine the radioactive decay. Half-Life.

How do you think archaeologists, when studying ancient pottery shards, determine how old their discoveries are? Have you ever heard of a technique called carbon dating, used to determine the ages of these archaeological samples?

Development Say to students: The element carbon is an essential element in all living matter. Carbon is produced constantly as our atmosphere is bombarded by cosmic rays. It is incorporated into the carbon cycle, so that all living things, including you, contain radioactive carbon Living things have about 15 disintegrations per minute per gram of carbon.

Because living things constantly interchange carbon atoms, the amount of carbon remains constant, but when organisms die, no new carbon enters the organism. However, the carbon that was in the organism at death continues to disintegrate. By measuring how much carbon is left in a sample as well as its radioactivity, we can calculate when the organism died.

It's a way of working backwards to solve a puzzle. In this activity, you will work backwards to solve a puzzle, much like scientists work backwards to find the time that an organism died.

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

You may group them in any size group, but working in pairs is optimal for this exercise. The lab stations should have been set up already as described in the Planning Ahead section above.

Students should complete the Analysis section of the lab sheet, which will be used as part of their assessment. Advise students to read through the case first so that they understand what they should do.

## Frosty the Snowman Meets His Demise: An Analogy to Carbon Dating

Written below is the case as it appears on The Case of the Melting Ice student sheet. There were no eyewitnesses, but there are several suspects. All the suspects have holes in their alibis. You need to determine the exact time at which Frosty was put into the funnels to melt away, leaving no trace. On a separate sheet of paper, immediately record the volume of Frosty's melted remains water in your graduated cylinder and note the time on the clock. Make a data table and, at regular intervals you decide how longrecord the time on the clock and the volume of water in the graduated cylinder.

### Lesson: evolution: Date a Rock

Stop after about 30 minutes, unless Frosty has completely melted earlier. Students should answer the questions on their student sheet based on their graphs and the data they collected. This page has been archived and is found on the Internet Archive. Assessment In addition to using answers to students' Analysis questions and their graphs for evaluation, consider having them respond to the following in their science journals or as a homework essay: How do we measure the ages of rocks?

Count "atoms" in simulated rock samples of different "ages". Students relate half-lives of radioisotopes to the application of dating rocks.

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

Sequence all known radioisotopes with half-lives greater than 1 million years; look for pattern, showing that all longer-lived isotopes are still with us, and the shorter-lived ones are not, indicating a finite age of our solar system, and that its age must be in the millions or billions of years. Do the Deep Time lesson, which emphasizes why we are so confident of geological age dates. Do the Virtual Age Dating Tutorial onlinefor further reinforcing of half-life concept and how this is applied to dating rocks.

This is especially helpful in explaining how isochrones work, and why they are so compelling. Consider using other items to replace the beans and popcorn. Also consider permanently sealing each set in its plastic bag, if you have such a device.

If you have a fair number of math-literate students, consider providing a number of bags "rock samples" with ratios other than precise half-life proportions, and have class create a half-life curve and figure out the age of their particular samples according to where they fit on the curve. Encourage or even facilitate students to do the online Virtual Age Dating Tutorialusing a high speed internet connection, with the prospect of earning their official "Certificates of Completion as a Virtual Geochronologist".