This lesson focuses on 4.NBT.B. and 4.NBT.B.5, using place value understanding to multiply two-digit by two-digit numbers. Students work with area models, the standard algorithm, and a real-world problem to practice, develop, and share understanding of multi-digit arithmetic. Core Actions 2 and 3 are clearly evident in this lesson.
Multi-Digit Arithmetic (Ussary)Download
In this part of the lesson, the teacher is using an area model to represent a two-digit by two-digit multiplication problem. She demonstrates how to create the size of the parts on the model to represent the larger and smaller numbers. She encourages students to think about the powers of ten when they are multiplying by tens. This gets at 4.NBT.1.
Here, the teacher models mathematical language appropriate to the grade and sets the expectation for students to use this language as they talk through the steps in using the standard algorithm to solve the same multiplication problem as they did using the area model.
In this part of the lesson students are sharing their thinking, verbalizing the mathematics they are doing in order to use the standard algorithm to solve the problem. They are responding to questions from the teacher and finding their own errors.
In this part of the lesson, students are working on a high quality problem with a partner. Students are sharing how they are thinking about the mathematics of the problem. The teacher can be heard asking questions to the students, prompting them to share their thinking - including one student whom the teacher guides to think about the problem as something concrete.
In this part of the lesson, students can be heard discussing different models to use to represent the math. Towards the end of the clip, you can hear a female student sharing, in response to another child, how she knows her method works.
The teacher has been walking around questioning students about their problem solving methods and understanding of the mathematics. One student shares his confusion with the teacher - the same confusion she has addressed with other partners. She interrupts the whole class to explicitly address the confusion by correctly drawing and labeling a model to represent the problem.