Title: Lesson 7: Using Clocks to Subtract Fractions with unlike denominators
Standard(s): 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).
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.
SMP#2 Reason abstractly and quantitatively.
SMP#7 Look for and make use of structure.
Lesson Overview: This lesson will review the previous days skills learned. This lesson will take the introduction of adding clocks on fractions to now subtraction fractions with unlike denominators.
Resources or Materials Needed
Time: 60 Minutes
Step 1: Pre-Instructional Activities
Standard(s): 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).
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.
SMP#2 Reason abstractly and quantitatively.
SMP#7 Look for and make use of structure.
Lesson Overview: This lesson will review the previous days skills learned. This lesson will take the introduction of adding clocks on fractions to now subtraction fractions with unlike denominators.
Resources or Materials Needed
- T Chart
- Blank clock template (Appedix C)
- White Boards and Markers
- Pencils
- Notebooks
- Anchor Chart Paper
- 10 x 10 grid paper
Time: 60 Minutes
Step 1: Pre-Instructional Activities
- Students will have a discussion about what they have been working on the past two days
- The teacher will prompt them to see if they know of anything they could do to extend the use of clocks and fractions.
- The teacher will guide them that they can use the clocks to subtract fractions.
- The teacher will review the previous day’s problems with the whole class to make sure they understand how the clock works.
- The teacher will introduce a problem they have not tried yet, 3/4 + 1/2=
- This problem will introduce subtracting fractions to the students.
- The students should be given time to complete this problem with their shoulder partners before the teacher shows how to complete the problem.
- The teacher will show the students another example of a subtraction problem
- Teacher will ask the students to complete
- 2/3 - 1/6=
- 3/4- 1/2 =
- 2/3 - 3/4 =
- 11/12 - 1/4=
- For each problem students will use a new blank clock template
- The teacher may need to pull small groups to check for understanding.
- A pre-assessment indicated that the students do not have a very good understanding of fractions, specifically adding and subtracting fractions with like and unlike denominators
- The teacher will circulate around the room during the group time and observe student’s understanding of the content
- Students will complete a post assessment at the end of the instructional unit
- Students will be asked to complete a brief assessment at home:
- Discuss with their parents why and what they call different times of the day. I.E. Quarter to (15 minutes to the hour)
- Students will be asked to use www.khanacademy.org for a follow up activity. The teacher will assign them a task on the website in order to check for understanding of the content.