## Reflection: Debate Evaluating Functions Day 2 - Section 1: Open

Sometimes it is difficult to pose a question that students can debate using mathematical language. Because mathematics often yields right and wrong answers, students are often not ready to debate the accuracy of an explanation.  However, debating also means justifying your thoughts which is a mathematical practice that successful mathematicians exhibit.

Today's opening question was great for creating the environment for a debate.  The non-verbal cue revealed that the class was about 60%:40% on the correct value of f(2). The majority of students said the output value should be 4.  But the remainder of the students either thought that there was no output value or that the output value was 3.  I was able to keep from tipping my hand to show (either verbally or non-verbally) what the answer should be.  I let the students make arguments and counter-arguments until they came to the conclusion that the solution should be 4. There was some significant time spent processing the debate (which I did somewhat anticipate), but it was time well spent for the opportunity for students to engage in mathematical practices (MP3).

A fear for some teachers when debates arise is that while you have 4-5 students discussing an idea or a solution publicly, the other students are "opting-out."  I used a turn and talk at the end of the discussion to get all students in the class talking about what was said and why the solution came out to be f(2) = 4. This strategy appeared to work well.

Opening-reflection
Debate: Opening-reflection

# Evaluating Functions Day 2

Unit 1: Functions
Lesson 13 of 18

## Big Idea: Students who understand functions well can make connections between the graph of a function and the equation of the function.

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Standards:
Subject(s):
Math, Algebra, domain, range, evaluate, input, output, function, function
40 minutes

### James Bialasik

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