In this unit , students explore four models of addition (counting, number line, sets, and balanced equations) using dominoes. They also learn about the
order (commutative) property, the relation between addition and subtraction, and the result of adding 0. Students also write story problems in which the operation of
addition is required and begin to memorize the addition facts. In this unit, students also investigate properties of addition and represent addition in pictures.
Because familiarity with the many models of addition is important to students’ success in problem solving, four models of addition are presented. Together they provide a structure for developing a rich conceptual schema for addition.
Individual Lessons
Lesson 1 - Counting to Find Sums
This lesson focuses on the counting model for addition and begins with reading a counting book. Students model the numbers with counters as the book is read. Then they count the spots on each side of a domino and write, in vertical
and horizontal format, the sums suggested by dominoes. Finally, the students illustrate a domino and record a sum it represents.
Lesson 2 - Hopping on the Number Line
In this lesson, students generate sums using the number line model. This model highlights the measurement aspect of addition and is a distinctly different representation of the operation from the model presented in the previous lesson.
The order (commutative) property is also introduced. At the end of the lesson, students are encouraged to predict sums and to answer puzzles involving addition.
Lesson 3 - Exploring Adding with Sets
This lesson builds on the previous two lessons and encourages students to explore another model for addition, the set model. This model is similar to
the counting model in the first lesson, because it is based on counting. Reading a related counting and addition book sets the stage for this lesson in which students write story problems, find sums using sets, and present results in the form of a table. In the discussion of the table, the students focus on the order property and the effects of adding 0.
Lesson 4 - Balancing Discoveries
This lesson encourages students to explore another model of addition, the balance model. The exploration also involves recording the modeled addition facts in equation form. Students begin to memorize the addition facts by playing the “seven-up game.”
Lesson 5 - Seeing Doubles
In this lesson, the students focus on dominoes with the same number of spots
on each side and on the related addition facts. They make triangle-shaped flash
cards for the doubles facts.
Lesson 6 - Finding Fact Families
In this lesson, the relationship of subtraction to addition is introduced with a book and with dominoes. Then students explore the concept of missing addends.
