Reflection: Real World Applications What is a Function? - Section 2: Introduction + Guided Practice


Multiple examples: Today's topic can feel very abstract for some students, especially for those who have never been introduced to the idea of a "function" in math. The more real world examples I am able to use in my explanantion of a function, the better students are able to conceptualize what is going on.

I stray far away from the explanation "it's not a function if the first number repeats". This brief "shortcut" allows students to answer numerical questions, but fails to help them understand the significance of functions in mathematics. It also hinders their success for future lessons that need students to think critically about domain, range, and algebraic relationships.

Additional examples that I have used to describe a function:

-number of cats vs. number of legs --> which relation is the most resonable? {(1,4) (2,8) (2,8) (3,12)} or {(1,4) (2,8) (2,9) (3,12)} Which relation is a function and why? Are you able to predict the output for each input? 

-day of the week vs. temperature

-y = x + 3. when x is 4 the output is usually 6, but sometimes the output is 7. Is this a reliable situation? Will you always know what the output will be when "4" is inputted?

-Draw two "function machines" on the board: Examples

  Multiple Examples
  Real World Applications: Multiple Examples
Loading resource...

What is a Function?

Unit 2: Linear & Absolute Value Functions
Lesson 1 of 10

Objective: SWBAT identify functions from ordered pairs, a table, a graph, and a mapping diagram.

Big Idea: Students will identify whether a relation is a function by examining its inputs and outputs or with the vertical line test.

  Print Lesson
103 teachers like this lesson
soda machine cropped
Similar Lessons
Graphing Radical Functions Day 2
Algebra II » Radical Functions - It's a sideways Parabola!
Big Idea: Looking back over a number of examples, students make use of the structure of equations to anticipate the graph.
Fort Collins, CO
Environment: Suburban
Jacob Nazeck
The Function Game
12th Grade Math » Functioning with Functions
Big Idea: Functions are investigated using a game that is accessible and engaging.
Troy, MI
Environment: Suburban
Tim  Marley
Choosing a Method to Find x-intercepts
Algebra I » Quadratics!
Big Idea: Students take a step back from their work to examine a variety of quadratic functions and reflect on why they might choose one method over another.
Boston, MA
Environment: Urban
Amanda Hathaway
Something went wrong. See details for more info
Nothing to upload