I blogged about the first part of our Intro to Algebra unit in 6th grade here. In this part of the unit, we finally get into the algebra stuff.
Before we start evaluating expressions, we talk about what variables are and what the purpose of them is. We review word phrases. I started this year by putting these words up on the board and having students classify them based on their operation.
After we have done a bit of large group practice with that, I have students do a card sort/matching activity. Once I have checked their answers, they can play memory. Some students have also played Go Fish with the cards as well.
I also use this Desmos card sort on another day to review this concept.
Then we get into evaluating expressions. This year I made a small tweak to how I introduce this to students. In the past, I would stand up in front of the class and tell students what you do when you’re asked to evaluate an expression. I’m really trying to get away from being the teller of information in my classroom and instead be the asker of questions to get students to explain the mathematical concepts to each other. Here’s the small change I made this year.
I put “x + 2″ on the board and asked if we could come up with a number answer for this. I saw several heads shaking no, and when I asked why, they told me, “We don’t know what x is.” Then I added to the board “x = 7″ and asked if we were able to come up with a number answer for this now. They told me we could and that the answer was 9 and then explained how they got that for an answer. I could tell that not all of my students had caught on yet or weren’t fully paying attention, so instead of me rephrasing what the student had just said, I asked, “Can someone else explain to the class how ‘Sue’ got 9 for an answer?” Then I put something like 4x + 3 up and repeated the same process.
It was a small change, but it felt SO much better than standing up in front of the class telling them a process to follow.
The first activity I do is something I created several years ago, and I realized last year when I did this that it’s pretty similar to Sara’s Add-Em-Up activity. I created 4 different sets of 5 cards. Each set of cards is printed off on a different color paper so that I can tell which set students are working on. Below is a picture of the first page of the document for this activity which has 4 copies (each column) of the first set. I have 8-10 copies of each set. Because all 8-10 sets are the same color, before I laminated the cards, I wrote a number on the back of each card in a set. This way, when I find a random card on the floor I can ask, “Who has the red 3s?” and easily figure out where the card goes.
Students are put in groups of 2-3 and in their group they work together to evaluate each of the cards. When they are done, they add up their 5 answers and come tell me what they got. If they are correct, I will give them the next set. If they are incorrect, I don’t tell them which one they got wrong, and they go back to their group and work to figure out what they did wrong. I’ve tried to level the cards so that each set gets increasingly difficult. Set 1 has one to two operations on each card. Set 2 has three steps to each problem. The next set incorporates decimal operations and the final set has the variable in the problem more than once.
One of the reason I like having a different color for each of the sets is that it is easy for me to see where students are when we are doing this activity. If I look around my room and see one group on the red set (the first set for me) and every other group is on orange or green (the 2nd and 3rd set for me), I know I need to check in with the group working on the red cards.
Below is an example of each of the four sets.
As I was looking through my stuff to find the file for that activity, I came across another activity I created and had forgotten about. For this activity, I put students in groups and have them start at a problem. They can choose to solve either problem on the card. I encourage all students to try at least one of the more challenging problems. Once students solve the problem, they look for the answer on another card that I have hanging around the room and then solve either problem on that card. Eventually, they will loop through to all of the problems and end back where they started.
I also used this Desmos card sort towards the end of the unit to review with students.
Find the Flub warm-ups are great for evaluating expressions.
In the past, I haven’t done much with tables in any of my classes, and I know that this is something I should do more of. I added this Desmos activity to this unit, and overall I was pleased with how it went. It was challenging for some of my students, which was my goal when creating it.