This is a week-long unit exploring how to take Fact Family knowledge and use it to solve problems with an unknown number (4 + ___ = 9). The students should have an understanding of Fact Families before learning these lessons but there is a review on the first day. From there, the students will solve addition problem using manipulatives (number cards included) and then subtraction problems. The end of the unit is a review with mixed practice that challenges the students to solve and then explain how they figured it out. Enjoy!