This unit gives a very comprehensive and thorough lesson on fossils that form in sedimentary rock. The unit meets NGSS and Texas TEKS Resource System objectives 5.7a and 5.7d, along with Common Core objectives. The unit begins with a page on the formation of sedimentary rock. This includes diagrams and descriptions of how and where fossils form and can be found. Students are given instructions on how to make a sedimentary rock layer sandwich, with each layer representing a layer of rock. The sandwich also "traps" living organisms to demonstrate how they become fossils. Students are asked to analyze rock columns, with oldest layer on the bottom and younger layers in sequence above, to note changes in climate and environment in an area over long periods of times. Students are then asked to draw and describe their own rock layer column. Common fossils are pictured, from trilobites to ancient horses. They are compared and contrasted to current living organisms. There are several writing activites and students are asked to analyze diagrams and cross sections of rock layers. The unit is 24 pages long and gives you a lot for your money.