The lesson " Photosynthetic Prokaryotes" helps students explore the fascinating world of photosynthetic prokaryotes —the microbes that first learned to harness sunlight and transformed Earth’s atmosphere. Activities for students: Identify photosynthetic prokaryotes and learn why not all of them produce oxygen during photosynthesis Study cyanobacterial akinetes and heterocysts and their roles in survival and nitrogen fixation Examine a phylogenetic tree to locate photosynthetic prokaryotes