Math Background

Lesson: Modeling Addition
Introducing the Concept

Children first learn the concept of addition by joining 2 groups.

Materials: overhead projector; red and yellow overhead counters; number cards 1–6, a plus sign, and an equals sign

Preparation: Prepare number cards for 1 to 6, the plus sign, and the equals sign.

Prerequisite Skills and Concepts: Children should be proficient in counting and recognizing numbers to ten.

  • Say: I would like volunteers to help me act out a story.
    Have two boys come up to the front of the classroom.
  • Ask: How many boys are at the front of the room?
    Children should answer “two.” Have 1 girl come to the front of the room and stand apart from the 2 boys.
  • Ask: How many girls are at the front of the room?
    Children should answer “one.”
  • Say: Now one girl is at the front of the room. Let's count how many children in all are at the front of the room.
    Have the children count aloud to 3.
  • Ask: What did we do when we counted all the children at the front of the room? (We joined the 2 groups.)
    Continue bringing groups of boys and girls to the front of the room and counting the number of children in all, up to a total of 6 children.
  • Ask: What did we do each time?
    Encourage children to say that we joined two groups to find the total, or added.
  • Say: Now let's try this with counters.
    Direct the children to look at the overhead. Put 2 red counters on the overhead.
  • Ask: How many counters are on the overhead?
    Children should say “two.”
    Place one yellow counter on the overhead.
  • Ask: If I add one counter, what is the total number of counters? (3)
    Continue placing groups of red and yellow counters to a total of 6 counters on the overhead and having the children find the totals.
  • Say: Now let's learn how to write addition sentences.
    Put four red counters on the overhead.
  • Ask: How many counters do I have?
    Children should say “four.” Write 4 on the overhead.
  • Say: Now let's add one more.
    Place one yellow counter and write 1 on the overhead.
  • Ask: What is the total number of counters?
    Children should say “five.” Write 5 on the overhead.
  • Say: We can show how we added 1 to 4 and got a total of 5 by using math symbols.
    Write a plus sign between the 4 and the 1.
  • Say: This is a plus sign. It tells us that we are adding. Can you make a plus sign with your fingers?
    Model making a plus sign with your fingers. Then write the equals sign on the overhead.
  • Say: This is an equals sign. It tells us that the amounts on either side are the same, or equal.
    Continue as above, modeling different addition sentences with counters and recording them on the overhead. You may wish to have students volunteer to hold the number cards and the symbol cards that represent what you are adding on the overhead.

Houghton Mifflin Math Grade 1