Here is a lesson on rational and irrational numbers. It is a PowerPoint lesson which gives definitions for whole numbers, integers, rational and irrational numbers. Included is a 2 page student handout which includes these definitions and a place for the students to write these definitions. Also, there is a Venn diagram and 4 slides which involve a table where students will check if a number is rational, whole number, integer or irrational number.
This lesson addresses the content standard: 8.NS.A.1