This short lesson is focused on 5.NF.A.1 - adding fractions with unlike denominators by replacing the given fractions with equivalent fractions with common denominators. The students work independently to solve 1/2 + 2/3. Two students share their strategies at the board with an opportunity for others to ask questions and comment. This lesson exemplifies Core Actions 1 and 3.
Add Fractions with Unlike Denominators (Coverley-Paxton)Download
1B: Although this lesson is not introducing a new concept, the teacher connects the work students have done in the last lesson to the problem they are going to begin with in this lesson. The teacher lists strategies that were used in the previous lesson in order for students to begin thinking about how to solve this problem.
2B: In this part of the lesson, all students are given the opportunity to work on a grade-level problem. Students, working quietly on their white boards and in their math notebook to show their thinking, are trying to solve the problem: 1/2 + 2/3. While students are working, the teacher walks around and monitors student work.
2C: In this part of the lesson, the teacher calls on two different students to come up to the board and share their strategy and solution with the class. The first student who comes up uses models (squares) to show how she created equal parts (6 in each square) in order to add 1/2 + 2/3. She explains her thinking as she completes each step and comes up with the correct answer of 1 1/6. The second student comes up to the board and shares a strategy of listing the multiples of each denominator (2 and 3) in order to find a common denominator of 6. He then uses multiplication to create equivalent fractions of 3/6 and 4/6 to add in order to solve the problem. He also comes up with the correct answer of 7/6. During this time students are encouraged to ask questions in order to clarify their own mathematical understanding.
3D: In this part of the lesson, a student has just explained her strategy/thinking to the class and the teacher opens the discussion up to include all students, asking if anyone has any questions or comments for the student who shared. The first student disagrees with the strategy modeled because he doesn't believe the denominator can be changed to solve the problem (he says he solved it by leaving the denominators as 2 and 3). The teacher encourages other students to respond to this student's comment. Two different students explain how the strategy on the board is correct by re-explaining how the student solved the problem.
3A: Here, the teacher is trying to understand one student's thinking. She uses questions to get students to restate the focus of the lesson. She asks questions such as, "Why do we need to have common denominators when we add or subtract fractions?" and "Why?" in order to assess the understanding of some students.
3C: In this part of the lesson, the second student sharing his/her strategy and thinking is at the board. As he is completing the problem, he explains the steps he took to solve the problem. He shows how to use a common multiple of 2 and 3 to determine 6 is the common denominator that can be used. The student (new to the class/school) is unable to name the strategy he uses, so the teacher engages the rest of the class to assist in explaining what he's doing. She has him repeat it back in order to support his understanding.