## Reflection: Checks for Understanding Cone Connections - Section 2: Activity 1: A straight forward problem

Some common issues I encountered with my groups and question or prompts I suggest:

1. Some students do not discrimate well between volume and area formulas. This is noted in calculations, choosing the wrong formula, and in writing units squared instead of units cubed.

• I ask students directly "what is the difference between area and volume"?
• I ask students to compare the cone and cylinder and tell me what their common base area is and how does it show in their formulas.

2. Some students make errors identifying which values to substitute in the formula. A common example was using diameter instead of radius. (with diagrams, I would make sure the figure clearly indicates whether its pointing to the diameter or radius) Another common error made in my class is confusing the slant height with the actual height of the cone. The slant height is not used in activity one but shows up further along.

• I ask students to tell me what each variable in the formula stands for and to point out to me where this length is in the figure. It's can be surprising to see what students point out as being the diameter, radius, or height of the cone.

I try to be aware of these common errors while students are working.

Common issues in my class
Checks for Understanding: Common issues in my class

# Cone Connections

Unit 10: Volumes of Cylinders, Cones, and Spheres
Lesson 3 of 7

## Big Idea: Having grasped the concept of volume, students use this understanding to solve real world tasks, this time involving cones.

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50 minutes

### Mauricio Beltre

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