Listen&Learn: Carbon Dating

How scientists determine the ages of fossils

Pre-listening vocabulary

• carbon: a common chemical element that is necessary for life
• fossil: the remains of an organism that lived a long time ago
• radioactivity: the ability of a substance to produce energy from the decay of its particles
• decay: to break down or decompose
• half-life: the amount of time it takes for half of a substance to completely decay
• estimate: to make a reasonable guess
• fossil fuels: natural fuels like oil or coal

Listening activity

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Gapfill exercise

Carbon dating is a that scientists use to find out the age of a fossil. All living things consume forms of carbon throughout their lives. A type of carbon called carbon-14 is radioactive, which means that it decays over time. Living things usually absorb carbon-14 through natural carbon dioxide in the atmosphere. Since every radioactive substance decays at a specific rate, scientists can use a substance’s half-life to find out how long it has . Carbon-14 has a half-life of 5700 years. Scientists can estimate an age for any fossil that has enough carbon-14 left to measure. However, carbon dating may become more as humans continue to use fossil fuels. Oil and put more stable carbon dioxide into the atmosphere, which affects the amount of carbon-14 that living things absorb. If a plant or an animal does not contain enough carbon-14 to measure, then finding its age will be much harder.

Comprehension questions

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Discussion/essay questions

1. Human fossil fuel use is a big issue. Carbon dioxide levels are getting higher, and climate change is going to affect the world in many ways. Are there any changes you’ve made in your life to help the environment? Are there changes you’d like to make in the future?

Transcript

Carbon dating is a process that scientists use to find out the age of a fossil. All living things consume forms of carbon throughout their lives. A rare type of carbon called carbon-14 is radioactive, which means that it decays over time. Living things usually absorb carbon-14 through natural carbon dioxide in the atmosphere. Since every radioactive substance decays at a specific rate, scientists can use a substance’s half-life to find out how long it has existed. Carbon-14 has a half-life of 5700 years. Scientists can estimate an age for any fossil that has enough carbon-14 left to measure. However, carbon dating may become more difficult as humans continue to use fossil fuels. Oil and coal put more stable carbon dioxide into the atmosphere, which affects the amount of carbon-14 that living things absorb. If a plant or an animal does not contain enough carbon-14 to measure, then finding its age will be much harder.