To review rational counting and to prepare for the exploration of addition, distribute a bag of buttons and one number cube to each student. Ask the students to roll their number cube and then make a set with as many buttons as the number of spots showing on the number cube. Ask for volunteers to say the number in their set of buttons and then write it. Now tell the students to make a set of one more and one less
button than the set they first made.
Group the students into pairs and give each pair two number cubes, a bag of buttons, and a strip of paper. Ask them to fold the strip in half, and then color one side of the paper red and the other side blue.
Display a class chart that is labeled “Number of Buttons on the Red Side,” “Number of Buttons on the Blue Side,” and “Number of Buttons in All.” Now ask the students to each roll a number cube and make a set containing the same number of buttons as there are spots showing on the number cube, with one student placing his or her set of buttons on the red side of the chart and the other student placing his or her set on the blue side. Then ask them to determine how many buttons they have when they join the two sets together.
To make the joining action more obvious, assign one student in each pair to place his or her hands around the two sets and say “whoosh” while bringing both sets of buttons together. On scrap paper, the other student writes in red the number of buttons on the red side, in blue the number of buttons on the blue side, and in purple the number of buttons in all. Then have the students switch
roles. Repeat several times.
When they have identified several sums, help each group to enter two or three of their findings on a class chart. After the students have made their entries, ask them to give examples of the terms “addend” and “sum.” Call on a volunteer to read one row of the chart. Then call on other volunteers to read other rows. Next demonstrate how to write the entries on the chart as addition sentences.
Encourage the students to record a few of their “whooshes” as addition sentences.
3 + 4 =
7
Now ask the students to put three buttons on the red side of their paper and four buttons on the blue side. Ask them to whoosh them together and record the addition sentence that tells what they did, using red and blue numerals for the addends and purple for the sum. Next, ask them to put four buttons on the red side and three buttons on the blue side and to predict how large the set will be
when they whoosh the two sides together. Ask them to use red, blue, and purple numerals to write the addition sentences.
3 + 4 =
7 4 + 3 = 7
Repeat with other number pairs until the students are comfortable with the idea that order does not matter when they are joining two sets and recording the results.
Ask the students to choose one of the rows from the chart and draw a picture illustrating that number fact, writing under it the addition sentence that the picture illustrates. Then distribute a copy of the Sums to 10 chart
to each student and ask the students to find the addends they just used, putting one finger on each addend. Demonstrate how they can bring their fingers together on
the sum. [Note that the addends and sum are color coded to match the chart they worked with earlier.] Now ask them to find the same addends in the other color and see if they get the same sum. Now have several children use their drawings and the Sums to 10 chart to explain the commutativity property in their own words. You may wish to display the drawings in the classroom or in a more public
place before adding the records to their portfolio.
