This is a simple Real Number System graphic organizer that can used when teaching students how to categorize numbers into subsets. This has been a great visual aid for teaching this skill and I have used it as a formative assessment by giving my students a list of numbers and a copy of this organizer then the students write the numbers from the list into the chart. Doing it this way makes it feel more like a "seat work" assignment more so than a "test". Grab this Real Number System organizer for FREE! Enjoy!