Inequalities - Negative Rule

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Objective

Students will be able to solve and graph inequalities with a negative coefficient for x.

Big Idea

Flip the sign? Seriously? That's what you'll hear during this lesson!

Launch

10 minutes

OpenerAs students enter the room, they will immediately pick up and begin working on the opener – Instructional Strategy - Process for openers.  This method of working and going over the opener lends itself to allow students to construct viable arguments and critique the reasoning of others, which is mathematical practice 3

Learning Target:  After completion of the opener, I will address the day’s learning targets to the students.  For today's lesson, the intended target is “I can solve and graph inequalities with a negative coefficient.” Students will jot the learning target down in their agendas (our version of a student planner, there is a place to write the learning target for every day). 

Explore

45 minutes

Inequalities Negative Rule Notes: Inequalities Negative Rule Explore Narrative The keys for this lesson are going to be precision (mathematical practice 6), perseverence (mathematical practice 1) and reasonableness (mathematical practice 3).  Students will need to be precise when completing the steps - being careful to remember to flip the sign when dividing by a negative.  Students will also be encouraged to check answers from their solution sets - is your answer reasonable? If I choose a random number from your shaded region will it work?  Finally, students will need to persevere! Getting inequalities right takes time!  The negative rule is tricky, and frustrating - practice practice practice!

Summary

5 minutes

Instructional Strategy - Table DiscussionTo summarize this lesson, I am going to ask that students have a table discussion considering the question – We flip the sign when we divide by a negative, but what about when we divide into a negative? This is a common question that students have when solving inequalities – so I want to make sure that the question is thoroughly discussed in class. Most likely it will come up during the notes, but since some kids check out during instruction, this summary activity gives the students another opportunity to discuss this common mistake.