I ended up loving my Introduction to Functions unit!  So far, it’s been my favorite unit in Algebra 1.  
The first day, I talked about domain and range and used my domain and range foldable.  You can see in the picture that I had my students highlight the domain and the range in the table, mapping, and graph.  Also, on the same page, I gave the definition for function and the Vertical Line Test.
Next, we did a card sort of functions and relations.  After only giving them the definition on the previous page, I had them work independently.  I checked in with them every two minutes or so.  I wanted them to THINK.  They did very well and I was impressed with their work.
The second day, I introduced function notation.  I have a previous post about how I teach function notation.  This function notation page corresponds with that post.  
I also used this function machine hamburger book from Math=Love.  We went back and forth filling in part of the hamburger book and part of the function notation sheet.  Next year, I want to somehow combine the two into a more cohesive set of notes, instead of jumping around.
I had a review day after these two lessons, because I thought my students would struggle.  However, when I gave them their quiz, almost every Algebra 1 student made an A!  Yay!
I also have pages for writing a function rule and views of a function coming up soon.
 
 



