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# Surface Area of a Triangular Prism - What shape is the base?

Lesson 12 of 18

## Objective: Students will be able to make connections to prior learning of surface area of a rectangular prism, which allows them to develop of a method for finding surface area of a triangular prism on their own.

## Big Idea: Students make connections to prior learning of surface area of a rectangular prism, which allows them to develop of a method for finding surface area of a triangular prism on their own.

*60 minutes*

#### Launch

*10 min*

**Opener: **As students enter the room, they will immediately pick up and begin working on the opener – **Instructional Strategy - Process for openers**. This method of working and going over the opener lends itself to allow students to construct viable arguments and critique the reasoning of others, which is **mathematical practice 3**.

**Learning Target: **After completion of the opener, I will address the day’s learning targets to the students. In today’s lesson, the intended target is “I can calculate the surface area of a triangular prism.”

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#### Explore

*45 min*

**Brainstorm: **Students will brainstorm how to calculate the surface area of a triangular prism, based on their prior knowledge (**MP 1**). They will have 3 minutes to discuss with their table groups. I will open the floor for discussion regarding how the students think we should approach the problem, and I will ask for a show of hands for who worked it out and got an answer of 214 in^{2}. I will work out this same problem for their notes example.

**Surface Area of a Triangular Prism Notes**: After the discussion, I will go into instruction on finding the surface area of a triangular prism. I will ask students to add the information to their foldable as well as their guided notes sheet. I will walk the students through finding the surface area by identifying the sides and their dimensions. Included in our discussion will be the formula for finding the area of the base – stressing that in triangles one must divide by 2, and the number of faces/bases that form a triangular prism. I will work out the two class examples using student input.

**Table Practice: **After the class examples, the students will work on 4 table practice problems. For each problem, I ask that they draw out the decomposed figure – 2 triangles, and 3 rectangles, labeling each with its dimensions. I will walk around and provide assistance as needed, and then I will take volunteers to work the problems at the board. It is important that when students work with these figures, they pay close attention to precision (**MP 6**) - did they include all of the sides? Did they use the correct 2D area formulas? Do they have the right units? Higher level students will make connections and derive formulas on their own (**MP 7 and 8**) for the triangular prism, however, at this age level I do not explicitely cover the formula.

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#### Summarize + Homework

*5 min*

**Table Discussion: **To summarize the lesson, I will ask students to turn to their shoulder buddy at their table, and discuss the differences between calculating surface area of a triangular prism and rectangular prism. I am hoping to hear students discuss the formulas for finding areas of the bases as well as the differing numbers of faces/bases on each figure. Based on my observation of conversations, I will ask a few students to share out. Summary Thoughts

**Homework: **With any remaining time in class, students will be asked to begin their homework. On this particular homework, I have given them the answers, and I ask that they show me all the work that leads up to those answers. That way, they know if they are on the right track. Philosophy on Homework

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- UNIT 1: Introduction to Mathematical Practices
- UNIT 2: Proportional Reasoning
- UNIT 3: Percents
- UNIT 4: Operations with Rational Numbers
- UNIT 5: Expressions
- UNIT 6: Equations
- UNIT 7: Geometric Figures
- UNIT 8: Geometric Measurement
- UNIT 9: Probability
- UNIT 10: Statistics
- UNIT 11: Culminating Unit: End of Grade Review

- LESSON 1: Relationship Between Circumference and Diameter - What is pi?
- LESSON 2: Circumference and Area of Circles
- LESSON 3: Area of Irregular Figures - How do you break up a figure?
- LESSON 4: Working Backwards with Formulas - How do I undo a formula?
- LESSON 5: 2D Figures - Review Time!
- LESSON 6: Composite Figures and Circles Test
- LESSON 7: Intro to 3D Figures and Cross-Sections - What shape do you see?
- LESSON 8: Volume of Prisms - How are base area and volume of a prism related?
- LESSON 9: Volume of Square Pyramids - What is the relationship between and prism and pyramid?
- LESSON 10: Volume of Prisms and Pyramids Fluency Practice
- LESSON 11: Surface Area of a Rectangular Prism - What shapes do you see?
- LESSON 12: Surface Area of a Triangular Prism - What shape is the base?
- LESSON 13: Surface Area of Triangular and Rectangular Prisms Fluency Practice
- LESSON 14: Surface Area of a Square Pyramid - What shapes are the faces?
- LESSON 15: Volume and Surface Area of Prisms and Pyramids Fluency Practice
- LESSON 16: Volume and Surface Area Review
- LESSON 17: 2D and 3D Volume and Area Test
- LESSON 18: Surface Area and Volume Centers -5 Days of Enrichment and/or Remediation