How I teach The Real Number System, Classifying Real Numbers, and Closure

This is part of my Unit 1 Interactive Notebook for Algebra 1. You can view the rest of it here.

1.1 – The Real Number System, Classifying Real Numbers & Closure

There’s nothing trickier than picking the very first topic to cover in all of Algebra 1. So many options, so what goes first?

To start the very first unit of Algebra 1 off, I begin by talking about the real number system and how we classify numbers.

Why oh why, is this where I start, you might ask?

Instilling this vocabulary is very important in helping students be able to hold fluent conversations about math. I can’t tell you how many students I’ve had in Algebra 2 (or Pre-Calc!) over the years that have asked “what’s an integer?” and they are unable to complete a problem that they otherwise would know how to do solely because they lack the basic vocabulary and don’t understand what the question is asking.

This is silly, and I want to prevent these things from happening as much as possible. Math really is its own language, and helping students learn it will allow them to be more confident and much more successful in the long run.

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