Day 74: Intro to Perimeter

6th Grade Math Standards: 4.MD.3 Apply the area and perimeter formulas for rectangles in real-world and mathematical problems. For example, find the width of a rectangular room given the area of the flooring and the length, by viewing the area formula as a multiplication equation with an unknown factor.

Objective: Determine the perimeter of a polygon

Agenda:

1. Estimation 180 Days 81 through 83
2. QSSQ 
3. Pepper
4. Perimeter Notes
5. Perimeter Staircase
6. Perimeter Practice 
7. Weekly Quiz

Assessment: Circumventing the room as students began the homework as well as while they worked on the perimeter staircase problem.

Glass Half-Full: The question on the perimeter staircase that really forced students to struggle was the question, "How many toothpicks are in the tenth staircase?" In one class, I put the timer on for four minutes and let the students work. One of my students worked it through with me in a way that I had not even anticipated. He said that each staircase had a certain amount of toothpicks that were not counted as part of the perimeter and that this along with the perimeter was done in a pattern. By combining the number of toothpicks in both patterns he got the number of toothpicks altogether.

This lesson got better as I went on in class. I started out by having students write down the first two stairs in their notebook and then physically constructing those two staircases in partners using paperclips which I have in surplus because of the Dan Meyer lesson we always use.

Next, I had them find the perimeter of those two staircases. Inevitably there are groups that calculate the inside of the second staircase, so we need to have an argument about whether the perimeter is 8 units (as it should be) or 10 units (which includes the two paperclips inside the staircase.).

Third, we construct the third and fourth staircases on paper and using the paperclips.

Fourth, we find the perimeter of those. Fifth students get the rule. Sixth, they apply the rule to staircase ten. Seventh, I overwhelm them by asking for how many toothpicks (or paperclips in our case) are required to make staircase ten. As I already stated, that question tripped everyone with one exception.

Regrets: I never explained today's weekly quiz which is an open response. I have had issues with the students writing this year in terms of very basic concepts. I'm not the best writer (I don't need to tell you, you're reading this...), but I learned at a young age to start a sentence with a capital letter. The students are not doing that with consistency this year. I'm not sure if this is a texting thing or a writing in math issue, but I actually had to write on the rubric that points will be deducted for lack of capital letters at the start of sentences.