Reflection: Checks for Understanding Find the Volume of Prisms Using a Formula - Section 3: Guided Practice


As I was watching students work, I kept seeing strange answers for problems GP2 and GP4.  Both of these show prisms that are not "sitting" on their bases.  For GP2, students said the volume of the triangular prism was 60 cubic centimeters.  For GP3, students were saying the volume was 540 cubic meters.  

When I asked students how they solved the problem the said "base times tall fills them all".  That of course is the quote of the mnemonic for finding the volume of prisms.  Only it is misapplied.  I had to ask students to tell me the name of the shapes on GP2 and GP4.  

I asked them to tell me what the base of the shapes were.  These are triangular prisms but they are "sitting" on rectangles.  It was a bit perplexing;  we have done plenty of work talking about the parts of prisms and how to identify the base.  

I asked them how to identify the base of a prism.  Eventually they realized that the bases are the faces that are opposite and parallel to each other. 

  How Do You Define the Base, Again?
  Checks for Understanding: How Do You Define the Base, Again?
Loading resource...

Find the Volume of Prisms Using a Formula

Unit 6: Geometry
Lesson 32 of 37

Objective: SWBAT find the volume of prisms using a formula

Big Idea: Move from the concrete to the abstract. Students turn the modeling of a prism's volume into an algebraic formula.

  Print Lesson
3 teachers like this lesson
Similar Lessons
Density of Gases
8th Grade Science » Heat Transfer and Interactions of Matter
Big Idea: This investigation uses a simple method that allows for capturing the gas released from a chemical reaction to help students determine the density of the released gas.
Brookline, MA
Environment: Urban
Ryan Keser
Area of Irregular Figures - How do you break up a figure?
7th Grade Math » Geometric Measurement
Big Idea: Expert students will lead the lesson as students apply prior knowledge of area to composite figures.
Elon, NC
Environment: Suburban
Heather Stephan
Vocabulary Foldable
7th Grade Math » 3-D Measurements
Big Idea: Do you know what the words mean?
Columbus, OH
Environment: Urban
Jada Jackson
Something went wrong. See details for more info
Nothing to upload