## Saturday, March 14, 2009

### Algebra 1: Introduction to Inequalities

I'm not planning our Algebra 1 classes this year, so I have not been producing much for it. But I did put together a scaffolded introduction to inequalities. The objectives are for students to:

• Compare numbers using a number line (i.e. "<" means "to the left of")
• Understand the difference between open and closed circles
• Graph the solutions of a statement like "x < 3"
• Understand graphically why adding/subtracting by any number or multiplying/dividing by a positive number does not change the relative position of two numbers, while multiplying/dividing by a negative number does. In other words, students should understand when and why to "flip the inequality sign" when solving inequalities.
• Solve and graph linear inequalities
Here is the file.

Nick said...

I just checked out your inequalities lesson last week and I really like the bubbled choices for inequalities, seems like a helpful way to get kids to notice the sign rules. I actually found myself starting a lesson on absoluate value inequalities with some fill in the blanks to direct the thinking a little bit more. Stuff like

|5 - 3| = ?
|3 - 5| = ?
if |x| = 5, then x = ___ or ___
if |x-2| = 4, then x = ___ or ___
if |x - ?| = 5 and x = 3 or -7, then ? must be equal to ____.

jd2718 said...

An idea that I use (although I haven't flipped open your worksheet)....

Graph numbers on the number line. Solid circle. Find an excuse to do the graphing a week or two in advance.

Solid circle means the number is included. We can circle a number just to point it out (I do that for zero on a bunch of number lines).

Then, when the inequality comes, when I model board work I always start with an open circle. "Should we include 7?" And if they respond yes, fill it in.

I have much better luck than I used to.

Jonathan