This lab aims to teach students about the nature of carbon, the different types of compounds it exists in (e.g. charcoal, glucose, carbon dioxide), the biochemical reactions it takes part in (photosynthesis and respiration), the range of processes that carbon and carbon compounds are involved in on Earth, and how these link together to form the carbon cycle. In this activity, carbon dioxide is released from some chalk (calcium carbonate) by mixing it with vinegar (a solution containing a weak acid). Students will be reminded that animals get their carbon by eating plants and/or other animals and when oxygen combines with food in cells during respiration, carbon dioxide is released into the atmosphere as exhalation. Some of the carbon dioxide from the atmosphere is stored in the ocean and used by marine organisms to make their hard parts of calcium carbonate, including the discs of calcareous algae that form much of the chalk.