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Surface area of rectangular prisms
Today’s Lesson: What: Surface area of rectangular prisms Why: . . . so I can calculate the surface area of rectangular prisms.
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Why does the SA formula for a rectangular prism have 3 separate parts ?
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Let’s build a Rectangular prism . . . “Surface Area Net Activity”
(teacher will give directions)
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Let’s fill in the data from the prism we built . . .
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The formula explained . . . six bottom left pair SA= 2lw + 2lh + 2wh
There are ____________ faces in a rectangular prism! The top and ___________________ faces are congruent, the front and back faces are congruent, and the right and _______________ faces are congruent. This is why there are three separate “clusters” in the SA formula– each represents a congruent ______________ of faces! six bottom Bottom Left Back left pair
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Take a look: Surface Area Formula Animated
Website with animated explanation . . . Surface Area Formula Animated
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Apply the formula: 1) SA= 2lw + 2lh + 2wh 12 cm 5 cm 4 cm SA = 256 cm²
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SA = 168 cm² Apply the formula: 2) 2 cm 14 cm 3.5 cm
SA= 2lw + 2lh + 2wh 3.5 cm 14 cm 2 cm SA = 168 cm²
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Surface area word problem:
Bob is wrapping a present that is 12 inches long, 4 inches wide, and 3 inches tall. What is the minimum amount of wrapping paper required? SA= 2lw + 2lh + 2wh SA = 192 in²
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Wrap-it-up/summary: Why does the SA formula for a rectangular prism have 3 separate parts ? Because a rectangular prism has six faces– or 3 PAIRS of congruent faces.
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Finish homework worksheet (handed out in class).
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END OF LESSON
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