Introduction of Parent Functions

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SWBAT graph the parent functions using t-tables, and identify the domain and range.

Big Idea

To recognize the t-table as a strategy to use to graph all unfamiliar equations.

Warm Up

10 minutes

I start off this Warm Up by asking students the question, "How good are you at Pictionary?"

Teacher's Note: I took this activity from a website where a teacher was asking for help teaching domain and range that I will cite at the end of this narrative.  The Warm Up will need to be cut into individual graphs.

I intend for this Warm Up to take about 10 minutes.  I hand each student a small blank coordinate plane and one with a graph on it.  I instruct the students to put a folder between them, and to take turns explaining the graphs to each other.  One person verbally explains the graph, while the other person attempts to draw it correctly. The person giving verbal instructions cannot look at the graph the other person is drawing while they are explaining it. Then they switch roles, in order to give each student the experience of the illustrator and the one verbalizing the directions. 

When reviewing the Warm Up with the students, I have a few pairs of students share their experience.  I have the students share the words they use to describe the graph, and how effective the illustrator was from the instructions.  Students have been introduced to domain and range in a previous lesson, and some students do state the correct domain and range.  I have students show their illustrations on the document camera compared to the original graph.  I write the list of words that students share on the board.  An example of that list is below.

  • It is shaped like a heart.........
  • It starts at (2,3), and stops at .......
  • It has a hole at.....
  • It keeps going
  • Turn left
  • Turn right
  • It is increasing from 2 to 8
  • (0,9) is the highest point

After listing as many words as possible, it leads me into the lesson about how important it is to describe graphs with the correct math vocabulary.

Student Research Notes

30 minutes

The purpose of this lesson is to introduce students to some of the Parent Functions, and the vocabulary used to explain graphs. After reviewing the Warm Up, I hand students a list of Graphing Vocabulary, and a Graphic Organizer for students to take notes on the Parent Functions.  

I give my students the task of developing the notes for a Parent Function on their own.  I did not want to lecture on all the key features of the different Parent Functions. By asking my students to create their own notes,  my  students are using their own skills to graph the Parent Functions, compare their key features, and take notes on the features of each type of function.

By the end of this activity, I expect that my students will also realize how powerful a tool a t-table is when graphing a function about which little is known (MP5).  


10 minutes

After students have worked on the Notes of the Parent Functions independently for about 30 minutes, I begin to let pairs of students compare their notes.  If some students finish early, I allow students that are finishing to begin comparing notes.  Students are to check if their tables, graphs, and key features identified are the same.  If they are not the same, students are to discuss the differences to either come to an agreement, or present as an argument as we are reviewing the Notes as a class.  I have provided a  Key to the Introduction to Functions as a sample of information that I am expecting from students. 

As I am reviewing the notes students created to describe the Parent Functions with the class, a key feature that I have students focus on is the key point that we would focus on if the function moved.  I explain that in the next lesson we will be looking at different movements (or translations) of the Parent Function as we learn a topic called transformations. It will be important to identify a key point in each function to follow for these transformations, even though all the points move the same way.