Begin the lesson by modeling how to complete number patterns which involve addition. For example, give the students the pattern "2, 5, and 8," and ask them to name the next number in the pattern [11]. Ask students what the rule is. [Add 3 to the previous number.] Repeat this with other addition number patterns, such as 3, 6, 9, ____ or 4, 8, 12, ____.
Then give each student crayons and a copy of the Hundreds Chart Activity Sheet. Ask the students to color the following numbers blue: 3, 12, 21, 30. Call the students' attention to the sum of the digits in the shaded squares. [The sum in each case is 3.]
When they are ready, ask them to look for and color any patterns involving addition of the digits in the numbers. Allow them a few minutes to do this, and then invite them to share the patterns they found. An example that shows one possible pattern for adding the digits is in pink in the chart below.
As a challenge activity, invite the students to discover the pattern shown in yellow in the chart above. [The sum of the digits increases by 1.] You might have students gather around computers to observe this chart, project the chart using a projection device, make a color transparency of the chart and project it on an overhead, or provide individual color copies for groups of students.
Next, call the class together around computer(s) and introduce the Calculator and Hundred Board tool. As the students enter two addends, a plus sign, and an equal sign into the calculator (for example, 4, +, 5, =) on the tool, the square on the hundred board that shows
the sum (in this example, 9) changes color.
Invite pairs of students to take turns using this site to add numbers of their choice. Then ask a volunteer to use the calculator to show the sum 5 + 6, record it, then enter 6 + 5, record that sum, and compare the results. Encourage the students to try reversing the addends with other pairs of numbers. Have the students describe their observations orally. Finally, introduce the students, if needed, to the formal term, "commutative," and discuss the meaning of this
concept. Ask them how knowing this concept can help in learning number facts. For example, if they know that 3 + 4 = 7, then they also know that 4 + 3 = 7.
Assign the students to groups of three to five each, and give each group two number cubes. Have the students each take one turn rolling the number cubes and naming the sum. Encourage them to name the sum from memory if they can, or they may use counters or a
calculator if it is a sum they do not know.
Have each student write his or her sum on a piece of paper. When all the students have recorded their sum, ask the member of each pair with the highest sum to draw a circle around it. If more than one student has that number, each should circle it.
Allow the students to play several rounds. Then have them count the number of sums they circled. The one with the most circled sums is the winner of the game. The first four Questions for Students, as shown below.
To conclude the lesson, display an addition chart and help the students explore the chart by asking the last five questions from the Questions for Students section below. Next, give each student a copy of the Facts I Know Activity Sheet and ask them to enter the addition facts that they know from memory.
Tell the students to put their Facts I Know Activity Sheets in a safe location, because they will be using this chart in upcoming lessons.
