Math Intervention 3–5 Grade

34 Addition and Subtraction Concepts

What is the Joining Sets Concept?

Joining sets is an addition concept. Joining sets involves

combining quantities and fi nding the total. Each set that we

join is considered an addend. The total of the combined sets

is the sum. For some students, the introduction of symbols

(+, =), equation formats, and rules come before they have

established an understanding of what it means to join sets.

These students often struggle with addition because they

are trying to remember symbols, formats, and rules that

are meaningless to them. It is critical that we help students

develop a true understanding of joining sets so that the

symbols, formats, and rules make sense to them.

CCSS

Operations and Algebraic Thinking

Number and Operations in Base Ten

Formative Assessment

To fi nd out if a student can join sets use the following number

stories. Ask students to explain how they fi gured out each

answer with words, pictures, or models.

Michael has three cookies. Carlos gives him two more cookies. How

many cookies does Michael have now?

Gloria has large books and small books on her shelf. There are four

large books and fi ve small books. How many books are on Gloria’s

shelf?

Ten girls line up. Four boys line up. How many students are in the

line?

Joining Sets

CONCEPT: