Grades K-2: “Doubling Addition Facts”
From Mastering the Basic Math Facts in Addition and Subtraction
by Susan O’Connell and John SanGiovanni
Grades 3-8: “Notice and Wonder Activities”
From Powerful Problem Solving
by Max Ray-Riek of The Math Forum
Grades 6-12: “Proportions and Percents”
From Lessons and Activities for Building Powerful Numeracy
by Pamela Weber Harris