Think About Adding Nothing and a Little More
Lesson 5 of 8
Objective: Students will be able to have automatic, accurate recall of addition facts with 0, 1, and 2.
I begin this lesson by having the students to think about addition facts fluency.
Why is it important to know your addition math facts? What does it mean, to add?
Students have a brief time to turn and talk about what it means to add.
How is adding different from counting? How is it the same?
If necessary, I guide students to think about addition as joining and to visualize (make a picture in their heads) of what they know about how to write addition sentences.
Develop the Concept
Have the students pick up 4 of their cubes. Ask the students to add zero cubes to their cube train. Most often the students don’t do anything. Then I say, “I asked you to add zero cubes, how come you didn’t do anything?”
Why didn’t anyone add any cubes to their train? Then, I ask the students if they could write a number sentence for what we just did (4 + 0 = 4). I choose my words carefully here to refrain from asking students to write an addition sentence. I want students to get into the habit of thinking about and determining the operation, and not relying on the teacher to provide them with the operation.
Next, I have the students pick up 5 of their cubes. I tell the students that adding zero was an easy one, now it’s going to get REALLY challenging! I instruct them to add one cube to their train. When they are done, students are told to hold them up, pretending they are the Statue of Liberty. This is a strategy I use a great deal, with manipulative and individual white boards, as it tells me what students know and can do, but keeps up the pace of the lesson.
Then I ask them if they could write a number sentence to show what they just did (5 + 1 = 6), and when ready, to show their boards.
Finally, I end with the most challenging problem. Students show 3 cubes in a train and are asked to add 2 cubes to that train. Students show, and then write the number sentence (3 + 2 = 5).
Practice the Concept
Now that the idea of what we are doing today has been introduced, I ask my students to turn and talk about how this strategy of adding 0, 1, and 2 could help them build their math fact fluency.
I'm listening, but if necessary I guide students through questions to how adding 1 is just like counting, and adding 2 is just like skip counting by twos. When they are recalling number facts and building fluency, relying on what they already know is a strategy in determining the sum of an addition problem.
Students work in partners to complete the Try It Together game. In this activity, children solve both addition number sentences with 0, 1, and 2, and determine the missing addend in an addition number sentence. The students use number tiles and a bag to compete the activities.
Have students come back together as a class. Encourage students to turn and talk about what they learned adding 0, 1 and 2.
How could this be a useful strategy? When would you use it?
Have students share their responses with the class, using mathematical vocabulary and complete sentences. This practice is critical to the development of mathematical thinking, and can be supported with sentence frames, such as, "I know that the _______________ (missing addend, sum) is ___________ because ______________ (I counted on my fingers, I know that x is 1 more than y, etc.).