I begin by having the students turn and talk about what they remember about how they can use a part/part/whole model to show an addition problem. I make sure that my copy of the Part/Part/Whole Model is visible as a concrete referent. Also, students will need 2 trains of 10 connecting cubes, in two different colors and their own Part/Part/Whole Mat.
I give my students a few minutes to think and discuss, and then ask then to share their understandings. And then, with great excitement, I share that we can use addition number sentences to help us solve real world math problems!
To practice today, I use a powerpoint to guide students through problems. This allows me more time to circulate as students are working and address specific needs.
I have students get their connecting cubes and part/part/whole mat. I use an organizational system in my classroom that develops student responsibility and independence, and part of that is demonstrated whenever we use math manipulatives.
We do the first word problem in the joining word problems powerpoint together. It is important to model for students the "thinking" (metacognition) that engages with the language of a word problem, so I don't rush through this first problem. Together, students create the part/part/whole model on their mat, and go over the number sentence and answer together.
We practice the problems on the powerpoint together, going through the four other Joining Word Problems.
Students are expected to independently draw the part/part/whole model for each problem and write the two addition number sentences for each model. We stop to go over each problem as a class, drawing the part/part/whole model and number sentences. This gives students opportunities to make sense of their own work, to make revisions, and to ask questions. I make frequent checks for understanding, as well as circulating while students work.
This practice together is designed to support student perseverance (or develop stamina -whichever way you want to look at it) (MP1). As we go through the thinking together, students are never too far away from assistance but, I'm not answering or solving the problems for them. I am, instead, guiding them using questions, such as:
Tell me the word problem in your own words. Tell me about what you are trying to find.
What do you notice about...? What information is given in the problem?
Describe the relationship between the quantities.
Tell me what you have already tried. What could you change?
The final slide on the PowerPoint asks the students to look at five word problems and try to "Spot" the word problems that are joining problems. Because my students often rely too heavily on key words, or the understanding that "We are learning about addition right now, so this must be an addition problem!", the students work in partners to read each word problem and then turn and talk about whether or not it is a joining problem. As the students discuss this I am circulating and asking the students to share their thinking. Is this a joining word problem? If yes, how did you know? What addition sentence would you use to solve this problem? If it is not a joining problem, how would you solve it?
To close, students are asked to do a challenging task - write their own joining word problems. I have students write word problems from the start of the year, and it doesn't begin easily for most of them.
I encourage my students to stick with it, and sometimes when we are thinking through word problems together I ask them to consider how they would tell this math story.
After they have created a word problem, it is shared with a classmate who is also done. And then they try to draw the correct model and solve their partner's word problem.