two students to the front of the room and ask the class how many noses
they see. Ask for a volunteer to write the number sentence that shows
that on the board. [1 + 1 = 2.] Now ask the class how many eyes they
see, and call for a volunteer to write that number sentence [2 + 2 = 4]
on the board directly under the previous equation. Now, have each of
the two students in the front of the room hold up three fingers, then
have a volunteer record the relevant number sentence [3 + 3 = 6]. Then
ask both students to hold up four fingers, then five fingers, and then
six fingers. Call on a volunteer to write each number sentence on the
Ask the class what these kinds of facts are called. [Doubles.] Then
point to the calendar and ask how many days are in two weeks, then add
the doubles fact 7 + 7 = 14 to the list on the board. Next, call on
eight students to wave their arms and ask someone else in the class to
tell how many hands the class can see. Record 8 + 8 = 16 on the board.
Finally, put 9 + 9 = on the board and ask the students what the answer
will be . Then, repeat with 10 + 10 =. Ask the students to look at
the sums to see whether they notice a pattern. [Possible answers are
that all the sums are even or that the sums increase by 2.]
Next to 2 +2 = 4, write 2 + 3 =, and ask the students what the
answer will be . Call on volunteers to explain how they know. Repeat
with other doubles-plus-one facts up to 9 + 10 =. Encourage the
students to say both the doubles and doubles-plus-one facts aloud.
Now assign the students to groups of four students each, and give each group two number cubes and a copy of the Tossing Sums
activity sheet. Tell them to take turns rolling the number cubes and
making an X in the column that shows which sum they rolled, beginning
at the bottom of the sheet. As they play, you may wish to move around
the room, noticing which students can name the sum immediately, which
students count on their fingers, and which students need to use
counters or other external aids, such as manipulatives.
After the students have played for several minutes, call the
students together and ask them what sums came up most often. Then have
them identify the sums that can be obtained only by getting doubles [2
and 12]. Now, assign each group one of the other even sums (4, 6, 8, or
10) and have them list all the ways they could get that sum. Then, ask
them to circle the double. Encourage them to share their work with the
class. Repeat with odd sums, having them circle doubles-plus-one sums.
Next, ask them to return to their seats and take out their personal addition charts.
Ask them to add to their charts any facts that they now know from
memory. Then have pairs of students exchange charts and ask each other
the facts that are marked on the chart. If a student misses a fact, ask
the partner to make a small dot or check mark by the fact to indicate
that he or she needs to practice it further.
As a record of this lesson, have the students write two addition
facts that they have recently learned and two facts that they wish to