Learning about Domain and Range

domain sorting activity

This week in my Algebra 2 classes, we began learning about Domain and Range. After first introducing the topic, I got a lot of blank stares. I got a lot of x values for range. I got a lot of domain intervals heading from infinity to negative infinity. Each year, I seem to add more and more to this unit, filling in the gaps from the year before, and this year is already shaping up to be no different. This week I decided to add a quick sorting activity to solidify domain (and to boost confidence and buy-in, which I see as the most important part of my job).

This activity was super quick for some students but took 15 minutes for others. Please excuse the hand-drawn graphs. I'm a little ashamed! But it's super easy to recreate.

absolute value

I love listening to my students to see where their misconceptions are. More often than not, their misconceptions are completely fascinating. One girl became very confused that, in the below picture, the domain went to positive infinity but the range came from negative infinity! And I see her point! I mean, the arrows are pointing down, right? This lead to a great discussion about the right arrow pointing down AND right. Domain will go to positive infinity but Range will come from negative infinity. Her questions reminded me of a poster I had squirreled away on my computer:

Buy in

About half-way through our domain and range unit, I give students this longer domain and range matching activity. I really like matching activities for this. There's a finite set of answers so students don't have to start from scratch to answer the problems, which gets all students engaged. 

Domain and Range Matching Activity

After matching all of the domain and range slips on to the cards, students sort their cards into 2 piles - function or not a function. It's fun watching them work together to figure it all out:)

Domain and Range Scavenger Hunt

I don't like giving quizzes, which I know is controversial. My students are super anxious from years of failure and I just don't feel right about perpetuating it. For many, Algebra 2 is their last math class. I want my students to leave high school with a good feeling about math so that they are more likely to go on to take more courses. Instead of a quiz, we complete a domain and range scavenger hunt to sum up our intro to domain and range unit. 

Review, Review, Review
To keep up their skills so that all this hard work doesn't get lost, we've been using the same quick check warm up template every day. I print a stack and give my students a new graph or equation each day. From there, they fill in the rest. 

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