# Carbon dating activity middle school

By extension, this experiment is a useful analogy to radioactive decay and carbon dating. Students use M&M's (or pennies and puzzle pieces) to demonstrate. How old is that fossil in the window? In this BrainPOP movie on carbon dating, Tim and Moby will teach you about how scientists use a radioactive isotope called. This is a slide and worksheet for radioactive dating and half life activity. The Slides are to be shown at the front and then each item is shown in turn and the.

Not all of the atoms of a radioactive isotope radioisotope decay at the same time. Rather, the atoms decay at a rate that is characteristic to the isotope. The rate of decay is a fixed rate called a half-life.

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

The half-life of a radioactive isotope refers to the amount of time required for half of a quantity of a radioactive isotope to decay. Carbon has a half-life of years, which means that if you take one gram of carbon, half of it will decay in years. Different isotopes have different half-lives. The ratio of the amounts of carbon to carbon in a human is the same as in every other living thing. After death, the carbon decays and is not replaced. The carbon decays, with its half-life of 5, years, while the amount of carbon remains constant in the sample.

By looking at the ratio of carbon to carbon in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing. Radiocarbon dates do not tell archaeologists exactly how old an artifact is, but they can date the sample within a few hundred years of the age.

Have the students spill out the candies onto a flat surface. Have the students record the number of candies they returned to the bag under the next Trial.

### Half-Life : Paper, M&M’s, Pennies, or Puzzle Pieces - ANS

The students should move the candies that are blank on the top to the side — these have now decayed to a stable state. The students should repeat steps 2 through 5 until all the candies have decayed or until they have completed Trial 7. Set up a place on the board where all students or groups can record their data. The students will record the results for 9 other groups in their data tables and total all the Trials for the candies NGSS Guided Inquiry Explain about radiation and half-lives of isotopes.

## In the Classroom

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. 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.

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.

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

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. 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: Pretend you are on a month-long field trip to dig for artifacts that might have been left from the pre-colonial period in the United States.

Write a letter to a friend explaining what radiocarbon dating is.

Relative/Absolute Dating

Be sure to include how radiocarbon dating works backwards to solve a puzzle. Explain to your friend how you and other archaeologists, with the help of chemistry, determine how old your discoveries are.