Adding & Subtracting Fractions

Prior to Lesson: This lesson does not take much prep. Each group needs a printed copy of each recipe. Each student will need a printed copy of the student record keeping sheet. Students need to know how to how to add fractions and have a basic understanding of the metric system to complete this task well.

1. Hand each group a copy of each recipe and each student a recording sheet.

2. Encourage students to look at different ways of solving the 3 problems in this performance task. Students must show their work and explain with models or words why they chose a specific strategy. Use the Questioning Prompts to further student thinking.

Extension: As a fun real life application in measuring and mixing, it is fun to make dirt cake with the students. It can be done very easily in the classroom, and the students can't get enough of it.

Focus Content Area Standards

CCSS.MATH.CONTENT.5.NF.A.1

Add and subtract fractions with unlike denominators (including mixed numbers) by replacing given fractions with equivalent fractions in such a way as to produce an equivalent sum or difference of fractions with like denominators. For example, 2/3 + 5/4 = 8/12 + 15/12 = 23/12. (In general, a/b + c/d = (ad + bc)/bd.)

CCSS.MATH.CONTENT.5.NF.A.2

Solve word problems involving addition and subtraction of fractions referring to the same whole, including cases of unlike denominators, e.g., by using visual fraction models or equations to represent the problem. Use benchmark fractions and number sense of fractions to estimate mentally and assess the reasonableness of answers. For example, recognize an incorrect result 2/5 + 1/2 = 3/7, by observing that 3/7 < 1/2.

Standards for Mathematical Practice

CCSS.MATH.PRACTICE.MP1 Make sense of problems and persevere in solving them.

CCSS.MATH.PRACTICE.MP2 Reason abstractly and quantitatively.

CCSS.MATH.PRACTICE.MP3 Construct viable arguments and critique the reasoning of others.

CCSS.MATH.PRACTICE.MP5 Use appropriate tools strategically.

CCSS.MATH.PRACTICE.MP6 Attend to precision.

CCSS.MATH.PRACTICE.MP7 Look for and make use of structure.

CCSS.MATH.PRACTICE.MP8 Look for and express regularity in repeated reasoning.