## Reflection: Adjustments to Practice Cylinder Volumes (Part 1) - Section 3: Closure

After teaching this lesson here are some thoughts and about what occurrenced:

1. Not one student stated that the long thin cylinder with the small radius had more volume. Most actually said they had the same volume due to having the same values for their dimensions, despite one value being the radius of the base and the other being the height of the cylinder. A few predicted correctly but with an inaddequate reason.

2. The lesson actually went well, but mostly with respect to the actual math work that was required. Students had little difficulty, if any, with calculations to find areas, the radius, or volume of the cylinders, but...

3. Despite it being a lesson where students had to explain their predictions and reason at certain points, I felt towards the end that they only had a vague idea if any, of why the difference in volumes between cylinders. They knew that volume meant the space inside but I felt they did not grasp the idea. This made me think that maybe part two of the lesson where volume is defined based on the unit cube,  could be taught first. Then again, it is true that students don't necessarily need to grasp a concept in its entirety immediately.

These were some of the comments by students.

• "I still don't know why the wide cylinder has more capacity....I did it here and it came out bigger (refering to the math), but I still don't know why" (This was at the end of the period so I had a chance to sit with her one on one)
• "I thought that the 2 in the lateral surface area formula was because there are 2 bases." (student knows that she needs to double the base area when finding total surface area)
• "Why doesn't the lateral surface area have r squared?" (this was actually a new student who came in one week ago....had to sit with her as well)
• A short review of area could have helped. Hence, the embedding of area  concepts in part 2 of the lesson.

After teaching the lesson...
Adjustments to Practice: After teaching the lesson...

# Cylinder Volumes (Part 1)

Unit 10: Volumes of Cylinders, Cones, and Spheres
Lesson 1 of 7

## Big Idea: Which cylinder is larger? Students make conjectures, then do the math.

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55 minutes

### Mauricio Beltre

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