One quality middle school alternative worth consideration is the 2002 release of Physical Science, Life Science, and Earth Science by Christian Schools International.
Here's a thumbnail sketch of topics covered in each text: Integration Much like the elementary editions, all three middle school volumes weave the Christian worldview throughout each text.
All living things exchange the gas Carbon 14 (C14) with the atmosphere around them—animals and plants exchange Carbon 14 with the atmosphere, fish and corals exchange carbon with dissolved C14 in the water.
Throughout the life of an animal or plant, the amount of C14 is perfectly balanced with that of its surroundings. The C14 in a dead organism slowly decays at a known rate: its "half life".
Radiocarbon dating is one of the best known archaeological dating techniques available to scientists, and the many people in the general public have at least heard of it.