Day 46: In-N-Out

Today students started Day 1 of In-N-Out by Robert Kaplinsky.  My whole department does this activity to kick off functions in Algebra 1. I did this activity last year and have made a few modifications…

We started by talking about our favorite fast food places. Since Montana doesn’t have any In-N-Out it is nice for a student to mention the place so it doesn’t come across as forced. Last year we started with the 100 x 100 pictures. I mixed things up this year and showed students a video instead.

At this point we dive into 3-Act world.

Write down the first question that comes to your mind.


The +6 shows that 6 other students found that question interesting.

In this period the main question How much would a 100 x 100 cost? didn’t come up. That’s ok. I helped them along.


We took estimates. Sometimes I get crazy low estimates and that doesn’t bother me. However, this year I have been feeling that students are starting to take advantage of the amount of openness they have in math… So I took a page from Andrew’s comment here and asked students “Take a minute to look at the range of estimates we have, convince why any of them might not make sense” 

I didn’t just blow off the fact that Alex’s name was attached to one of the estimates, after someone called him out, I gave him a chance to respond.

After I showed students what a cheeseburger and double double look like.


And asked them what they noticed about each.

They came up with pretty much everything; same number of buns on each, same condiments, different number of patties and cheese.

Students created a wish list of information they wanted to answer the question:


I added a new piece here that I REALLY liked… by asking students: what would you do with this information?

I then gave them this picture and set them loose to answer the question.


About half the class was done in two minutes.

There were two main misconceptions I saw….



Instead of showing these pictures right off the bat I asked students “I am seeing a lot of different calculations. If we use a double double to find the price, shouldn’t it be the same as using a single cheese burger to find the price?”

They agreed. Then we worked through $2.65(100) and $1.75(100). They weren’t the same. We talked about what they were calculating.

******A big difference this year… This incorrect answer seemed to be discouraging. Students weren’t even sure if the 100 x 100 existed. So at this point in time I showed them the picture


I loved the reactions and students had a good idea of how they needed to calculate the price.

In some classes we reached final calculations and looked at the receipt. I am saving that for the continuation of this post… coming tomorrow!


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