Ratios with Thinking Blocks
Lesson 4 of 21
Objective: • Create a bar model for a ratio • Use multiplication and division to extend a ratio.
See my Do Now in my Strategy folder that explains my beginning of class routines.
Often, I create do nows that have problems that connect to the task that students will be working on that day. Today I want students to review what they know about ratios. I want students to recognize that if the ratio of Claire’s stamps to John’s stamps is 2:3, then we know that John must have more stamps. I also want students to be able to extend the ratio. If John has 24 stamps, then Claire must have 16 stamps, since 3x8=24 and 2x8 = 16. A common mistake is to confuse the order of the ratio, or number of stamps. Students are engaging in MP2: Reason abstractly and quantitatively.
I call on students to share out their answers and share whether they agree or disagree with one another. I say that Claire must have 36 stamps, since 2x12=24 and 3x12=36. I want students to remember that the order of the values does matter. Students are engaging in MP3: Construct viable arguments and critique the reasoning of others.
- This lesson requires that each student have a laptop to access the Thinking Blocks problem sets.
- Before this lesson, I use the TTG from the previous lesson to determine which set of ratio problems students need to be working on with Thinking Blocks. There are 7 sets of problems that go in order of difficulty. I create a list that shows which color each student will start with. As students get their computers, I walk around and tell them their color they are starting with.
I mention that we have used bar models to model addition, subtraction, multiplication, and division problems. Today we will be learning how to create a bar model that helps us solve ratio problems. I review expectations about laptops with my students like, use two hands when you carry it, only visit sites that Ms. Palmer says to, and turn off your volume. I explain that there may be issues with the laptops (dead battery, faulty internet connection) and that they will have to show patience as we problem solve to fix them.
I call on a student to read through steps 1-3. As the student reads the steps, I model the steps on the projector. Then I call students up to get their own laptop and go through steps 1-3 independently. I walk around and let students know which color set they need to start with.
Once students are ready for steps 4 and 5, I read through them and model them on the projector. I tell students to double check that their volume is off. I project the video tutorial on the projector and students fill out their problem on their packet.
I tell students that they need to get 5 stars before they can move on and they must draw the models for two of those problems. I want students to practice drawing the models so that they can use this strategy when they are working with paper and pencil. I briefly model how to move on to the next set.
Students start on their own color set. As students work I walk around and monitor student progress. If students have questions, I review how they can check their work and get feedback from the website. The most common mistake is that students switch which information goes with which label. Students are engaging in MP1: Make sense of problems and persevere in solving them, MP2: Reason abstractly and quantitatively, and MP4: Model with mathematics.
I remind students that they must draw models for two problems in each set. I also announce when work time is half way over.
With three minutes left, I tell students to log off and plug their laptops back into the cart.
Closure and Ticket to Go
For Closure I have students return to the do now question 1c. I ask students how we could create a bar model for the problem in the do now. Students participate in a Think Pair Share. I ask students to share their model with their partner. Then I have 1-2 students show their model under the document camera. I want students to recognize how the bar models can help them work with ratio problems.