[If you're not interested in absolute value, there is a pretty funny story about a 3hole punch at the very end. Or, maybe it's not funny. Maybe it's sad. Either way, it was a memorable experience.]
This week, I started introducing the concept of absolute value to my Algebra 1 students. Our Algebra 1 textbooks introduce the concept of absolute value in Algebra 1. It introduces graphing absolute value equations in the same chapter where graphing linear equations is taught. Of course, I don't use the textbooks. I keep one by my desk as a reference, but the rest of the books are collecting dust on my shelves.
This summer, I had planned to introduce absolute value using the textbook sequence. I even created some pages for my students' interactive notebooks.
I never used this page, though. Actually, I decided it was in the best interest of my students to postpone discussing absolute value until later in the school year. When I started working with my students at the beginning of the year, I realized just how low many of them were. There were a lot of middle school math topics that I had to reteach. So, I made the decision to take certain concepts and postpone them until later in the school year. I was hoping that if I refined my focus I could build up my students' math levels and make them more confident. Then, with more confidence, we could start looking at concepts such as fractions, absolute value, probability, etc.
So, Monday was my students' first experience with absolute value in Algebra 1. A few students who took Algebra last year knew what absolute value was. A few others wrongly described absolute value as meaning the opposite. They thought it meant that you just changed the sign.
My students had been working really hard at multiplying binomials and factoring quadratics for the past two weeks. Test scores were not exactly where I had wanted them, but at the same time I was proud of my students because I have seen them grown an incredible amount since meeting them in August. In August, I would not have thought that my students would be factoring quadratics with a leading term greater than one. But, we've gotten here. We still need some more practice with factoring, but we will continue reviewing it and practicing it for the remainder of the semester. And, it was a Monday. So, I decided to kinda ease into our absolute value unit using the
Estimating Age activity from Dan Meyer's Algebra Curriculum (Week 3.)

Estimating Ages Chart 
I picked 15 of the celebrities from his file. I used their birthdays to calculate their current age. I typed up a halfsheet of paper for students to record their guesses. It's not perfect. After using it once, I realized that I should have added a fourth column for students to record the difference between the actual age and their guess. I don't know if it would be of use to anyone, but I have uploaded my file below.