This reading explains the development of life in the early Earth from bacteria and how photosynthesis in cyanobacteria and early plants filled the atmosphere with oxygen.  This is a good reading to use with the timeline of the history of life on Earth activity from the CUNY Evolution curriculum or as a stand-alone introduction to photosynthesis.

You may also want to use these writing skills practice questions based on this reading in order to incorporate writing practice into your science class.