Understanding Fractions with Visual Models by Jim Callahan & Marilyn Varrichio Develop conceptual understanding of fractions with this easy-to-use resource. Each of the 11 lessons use visual models to support learning and include instructions, questioning strategies, practice worksheets, and assessment pages. Throughout, students use fraction circles, squares, and number lines to reinforce their learning. Ideal for any student who needs instruction or review of the 3rd grade fraction standards.