8th Grade Unit 2: Inequalities (Part 3 -absolute value special cases and word problems)

The last part of our unit on inequalities covers absolute value special cases and word problems.  You can read about part 1 here and part 2 here.


Absolute Value Inequality Special Cases

To introduce solving absolute value inequalities that have no solution or all real numbers as the answer, I tried a couple different things this year.  In a couple classes I put this up on the board and we talked about each of them, which is what I had done in the past.

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In another class I put the following up on the board and asked how we could write an inequality that would never be true.

|x|______________

Then I asked how we could write an inequality that would never be true.  Once students gave me answers for that and understood, we talked about if it mattered what was inside  the absolute value bars.  Both ways worked fine, but I almost think I liked think I liked this new way better.  I liked that students were coming up with the inequalities.

The next day I started with the following warm-up problem.  I always like to include absolute value inequalities that don’t have all real numbers or no solution as the answer so that students don’t forget what they already knew about those types of problems.

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Here is the link to download a worksheet with these types of problems.

I also created an Open Middle type problem for these types of inequalities.  You can download it here.

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Absolute Value Inequality Word Problems

One of the things that my students need to know is how to solve word problems involving absolute value inequalities.  In the past, I just jumped into these types of problems, but this year I took a day to go over setting up the absolute value inequalities given a graph.  The day before this I had each student solve an absolute value inequality to use as this introduction.  You can download the problems I used here.

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I took several of these and had students find the midpoint of each graph and the distance from the midpoint.  Then students looked for a pattern.Screen Shot 2017-12-08 at 7.10.45 PM.png

Then I had students practice writing absolute value inequalities when given a graph and practice finding the midpoint of the graph and distance from the midpoint when given an absolute value inequality.

The next day when we got to solving word problems went so much better than it did last year having spent a day on this ahead of time.

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You can download the test review here.

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6th Grade Unit 2: Intro to Algebra (Part 4 -Inequalities)

The last part of our Introduction to Algebra unit in 6th grade is inequalities.  I also wrote about part 1, part 2, and part 3.

I don’t spend a ton of time with this.  I start with a few Desmos activities.  Polygraph is the first thing we do, and then I come back to it a day or so later after students have done more with inequalities.  Then we review the inequality symbols before students work on this Desmos activity.  It is a basic introduction to graphing, and it is usually the first time that my students see the greater than or equal to symbols and less than or equal to symbols.

The next day to review we start with this Which One Doesn’t Belong.

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Then we work a bit on graphing inequalities when given a situation.  This Desmos activity is one of the first things we do to practice this.

The last way we review is Mathketball.  My students LOVE this game.  They put their desks in a circle around the room.  I put a garbage can in the middle of the room.  I put a problem up on the board, and if students get it correct they get to try to shoot their paper in the basket.  Students would play this for every concept if I let them, but I try to save this for problems that I anticipate all students completing in the same amount of time compared to problems that have multiple steps to get the answer.

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I want to find more pictures like these that students can write inequalities for.

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The day before the test a student asked how many problems were going to be on the quiz.  I said, “8 problems tops.”  Another student said, “You should make us write an inequality for that.”  I just love these kiddos so much.

6th Grade Unit 2: Intro to Algebra (Part 3 -Equations)

You can read more about our Intro to Algebra unit here (part 1) and here (part 2).  In this portion of the unit we get into solving equations.

There are several things I do prior to actually solving equations to get students thinking algebraically.

I absolutely LOVE puzzles like this.

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One of my students caught something in this puzzle that I had missed the first time I solved it.

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In one of my classes we had some extra time, so I had my students create their own.  It was super fun to watch them get excited over this and to see their creativity in what they used in their puzzles.

 

 

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Then we used one of my online puzzles –Solve Me Mobiles, and one of my favorite movement activities, Balance Points.  I blogged about both of those activities here.

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When we play Balance Points I put an equation up on the board and with a partner, whatever the answer is students need to have that many body parts touching the ground.

 

 


When we get into solving equations, I stole Julie’s idea found here.  If you teach middle school and haven’t read that blog post yet, you need to stop and do that right now.  I’m not even going to say anything more about it to force you to go read it.  Most of my students will only work on one-step equations.  In some classes they’re ready for multi-step equations or some students in the class are.  Here is the link to download a couple worksheets I use and an add-em-up activity.

Open Middle also has some great one-step equation problems.

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8th Grade Unit 2: Inequalities (Part 2 -Compound Inequalities and Absolute Value Inequalities)

You can read about the first part of our unit on inequalities here.  In the next part of the unit we do some word problems, compound inequalities, and absolute value inequalities.


Word Problems

I know the word problems I give students aren’t very “real world” and that this is an area I need to work on -finding/creating better word problems for students and doing a better job of teaching them as well as incorporating them into class.  I don’t have anything fancy I do for these other than a couple examples together as a class and then partner practice.

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Compound Inequalities

I use Notice/Wonder to start our conversation on compound inequalities.  Then we do this Desmos activity.  I also like this Polygraph activity for compound inequalities.

This year I also realized I could make a connection between “compound inequalities” and “compound words” and “compound sentences” that students are familiar with already from their English classes.  Why did it take me so long to do this?

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The following day I use this Which One Doesn’t Belong? for a warm-up and then we go back to the image from the notice/wonder the day before.  I put numbers on the graphs and students write inequalities for each.

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I used one of Sarah Carter’s awesome questions stacks for practice on solving these types of inequalities.  You can download the file she shared here.

One of my classes got to Point Collector.  This was my first time using this activity with students.  It’s SO fun!

One of my students came up with this for the last challenge.  He didn’t quite follow the directions exactly, but I love that he wanted to get the maximum number of points.  I overheard him telling another student about it later on during the class period when they were working on something else.  His friend goes, “Oh, so you cheated the system?” 😉

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Absolute Value Inequalities

I tried a couple different ways of introducing absolute value inequalities this year.  In a couple classes I started with Notice/Wonder.  Then in another class I started with an absolute value equation such as 3|x – 1| + 4 = 19 and had students solve that.  Then I changed it to an inequality and asked students what they thought would be the same/different about solving the problem.  Both ways of introducing the topic were good for different reasons.  I think for next year I may try to find a good combination of both.

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We did some vertical non-permanent surface practice with solving absolute value inequalities at the whiteboards around my room.

I also used this Open Middle type problem I made.  You can download the file here.

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Here is the link to download the test review.

8th Grade Unit 2: Inequalities (Part 1)

After solving many different types of equations in 8th grade, inequalities are up next.  We start by reviewing graphing inequalities before getting into solving them.  Then we also work on inequalities that have all real numbers and no solution as answers.


Review of Graphing

Although students have seen inequalities and graphed them in the past, I’ve found that it is worth my time to spend a day or so giving students a quick refresher on this.  There are several great Desmos activities for this.  Here are a few that I’ve used and like.

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Solving

In the past I had an activity I used to get students to discover when the inequality symbol needs to be switched when solving inequalities.  It was sort of lengthy and cumbersome, but I didn’t know how to improve it more than I already had.  Then I saw Sarah Tweet the picture below.  It was EXACTLY what I was looking for!  Thanks Sarah!  Here is the link to download Sarah’s file.

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Then for practice students do a Tarsia puzzle.  I created the puzzle a while ago and don’t know where the file is that I can share.  If you’re unfamiliar with Tarsia puzzles, you can learn more about them here.

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I also have a question stack that I use for these types of problems.  You can read about Sarah Carter’s question stacks here.

 

 

 


All Real Numbers/No Solution

To introduce inequalities that have No Solution or All Real Numbers as the solution, I went back to what students already knew about equations like these.  I had students solve a problem similar to the one below and then asked them what inequality symbol we could replace the equal sign with that would make the inequality have no solution and the same for all real numbers.

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Then for practice, I had students work on this Desmos activity.

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I also tried creating an Open Middle problem for these types of problems after seeing a similar one Sarah created for equations.  I had one of my co-workers take a look at a different Open Middle problem I made, and he had a great idea from when he has used Open Middle problems in the past.  He suggested to start by letting students use whatever numbers they want, and then after they come up with a solution to restrict them to only using certain numbers.  I thought this was a great idea, so that’s what I did.  I started by telling students they could use any integers they wanted as long as they didn’t repeat any of the 12 numbers.  When a student came up with a solution, I said they could only use the integers -6 to 6.

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You can download the files for the Open Middle puzzle here.

Math Telephone

I used Sarah Carter’s Representations of a Relation Telephone activity last year.  You can read all about the activity in her blog post.  In short, it works just like the game of “telephone”.  A student starts by writing six ordered pairs on the bottom, passes the paper to the next person who creates the graph, who passes it on the the next person who creates the table from looking at just the graph.  This continues until you get to the top of the paper with the ordered pairs again.  If done correctly, the ordered pairs should be the same.

I really liked it, but I knew there were some tweaks I wanted to make the second time around, and it went much better this time.  Part of it could have been that I had already explained the activity once, so I did a better job of explaining it and anticipating where students would struggle.  The first year I did this I actually had one group start whispering ordered pairs into each other’s ears.  I don’t know if they just weren’t listening or if my directions were that bad…probably a combination of both.  Thankfully that didn’t happen this year!

Sarah also shared an updated version of her activity here which also helped as she’s included more instructions on the sheet itself.

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The first time I did this I made the mistake of having one piece of paper per group of 4-5 students.  What was I thinking?!  That meant for 10+ minutes about 6 students in my class were working while the others were supposed to wait patiently?!  Not my brightest move ever.  This year all students had their own paper so everyone was doing something at all times.  This went MUCH better.

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As I watched the activity with my first class of the day, I noticed that it was taking students FOREVER to just fold the paper, and one student commented, “Folding the paper was the hardest part of this!”  I found that rather than folding it in an accordion at first it worked better for my students if each person just folded the bottom representation under before passing their paper on to the next person -these instructions are also on Sarah’s updated version.

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Overall it was a big success.  I loved watching students look at where the mistakes were made when they were done, and the second time they did it several students were thinking ahead when they created their ordered pairs to try to make it “easier” or linear -which will lead perfectly into what we’re getting to later in this unit.  I even had a student who doesn’t usually get too excited about much of anything say, “This is actually fun.”

I was thinking today what other concepts this could be used for and remembered one I made last year for my 6th graders on exponents.  Since last year, I lost the editable version of the document I made, so I recreated it and added some of Sarah’s instructions to it.  You can download the file here.

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What other concepts could this idea be used for?

One Good Thing: Volume 3

It’s been a while since I’ve shared my “One Good Things” from the week.  Here’s volume 1 and volume 2.  It’s been a challenging few weeks, so I thought focusing on the good at the end of the week would be a good thing in and of itself.


My first hour students were working on “Number Muncher” the Monday after Thanksgiving break.  When I said it was time to be done, their response was, “What?? Can’t we just stay in math all day?”

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One of my students shared with me about his first Black Friday experience.  He was NOT impressed.  AT ALL.  Even though he got this huge thing of gum balls, he would be perfectly happy to never experience Black Friday shopping again.  Ha!

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We did an activity called Balance Points in 6th grade this week.  It’s always a highlight for the students AND me.  I don’t think there’s a single person in the room who isn’t smiling when we do this.

The second day we did this activity, this grouped asked if we could have an question with an answer of 5 because, “we want to do that one we did yesterday.”  🙂

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A student came to class with this shirt on.  I don’t know why I found it so funny that day, but I did.

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I used Desmos Point Collector for the first time with students.  I’m a fan!  I had a student do this for the last challenge.  Later on during the class period he was telling his friend about it who goes, “Oh, so you cheated the system.”  😉

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High school basketball games started this week.  My dad coaches and many of their games are streamed online so I can watch from home.  It’s the best!  I’m convinced that God made basketball a winter sport to help us get through Minnesota winters.

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A little Mathketball is always a good way to start a Friday.

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We were reviewing for an inequalities quiz and at the end of class someone asked how many questions would be on the test.  I said “8 questions tops”, and a student replied, “You should make us write an inequality for that.”  So we did.

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I was explaining to a group of 8th grade boys that if they do better on the test on a skill than they did on the quiz earlier in the unit, I will replace the quiz score with their score for that portion of the test, but it doesn’t work the other way.  I said, “If you ace the quizzes but bomb the test, I won’t replace your test score with 100%.”  After saying they understood, I walked away but overheard one of the boys say, “I always though ‘bomb’ was a good thing.”  I went back to ask about this and explain what “bombing a test” meant when I was in middle school and that I must be old.  They said it reminded them of a conversation they had with the art teacher this week about the word “dope”.  Did I mention that this art teacher is just a couple years away from retirement?!  I’m not THAT old!

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I finally got to use a couple of Open Middle problems I made and was overall happy with how students did with them.

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