To review locating plots on a coordinate plane, we play "Doggy, Doggy, Where's My Bone" on laminated coordinate planes. Each student pair has a coordinate plane grid; one partner hides a bone on the plane, and keeps it close to his/her chest. The other partner has 5 guesses to find the bone by guessing ordered pairs. (This is a version of Battleship.) "Doggy Doggy, Where's My Bone?" is a play on an "old" classroom game where one person (the dog) goes out into the hallway, and then comes back in to find a memo board eraser (the bone) that has been hidden in the room. While this game doesn't have an academic purpose, you find about 5 minutes to play it and remind students about when you played the version we're playing today.
I then solicit from students what kind of graphs we could make about dogs. My students mention the quantity of food could be graphed. As an aside, the laminated coordinate planes help me during this unit because my students like to draw "little box, little box, little box," instead of drawing ten vertical lines and 10 horizontal lines. They seem to waste a fair amount of time, and as I need them to focus on the task more, and not drawing lines, this seems to be a better way to go about it. In the future, students will focus on the path from point-to-point. Afterward, we view the short song, Coordinate Dog.
To introduce this task, I have students indicate what the purpose of the graph may be. "Why would we need to look at a dog's weight?"
This is a real-world task, and just as in reading, we have to think about what the author/creator is showing us this. This is teaching students to be analytical learners. Students answer that one idea is to see if a dog is being fed too much food, or if the dog is sick. This is what I hoped that they would infer.
Layla makes a line graph on a coordinate plane to show the weight of her dog Niki over her lifetime. Using the graph, students analyze it to determine:
a) How much did Niki weigh when Layla first brought her home?
b) How much did she weigh when she was 4 years old?
c) What was Niki's greatest weight, and how old was she?
Step 1: I alert students to notice that the ordered pair for the first point is (0, 4), and it represents Niki's weight when Layla first brought her home. We then answer that Niki weighed ___ pounds. (4). I've noticed that some students tend to ignore the y-axis as actually being where plot (info) could be found.
Step 2: (Think Aloud/Modeling): To find Niki's weight when she was 4 years old, find the x-axis, or the horizontal axis. Move up the vertical line parallel to the y-axis until you reach the point that lies on the graph. The point is exactly between 12 and 16 on the y-axis. The ordered pair for the point is ______. (4, 14) How much did Niki weigh when she was 4 years old? (14 pounds)
Step 3: (Think Aloud/Modeling) To find Niki's greatest weight, look for the highest point on the graph. The ordered pair for the highest point is _________ (8, 20). So, his greatest weight was ____ (20). He was how old? (8).
Using MP 7, students solve the following problem:
Robbie has $12 saved from his allowance. He adds $4 to his savings each week. How much money will he have after 5 weeks? Students use the coordinate plane to make a line segment that shows the relationship between the numbers of weeks he adds $4 and the amount of money Robbie has saved.
I encouraged students to look back at the graph of the line segment that they made to show Robbie's savings. I asked, "How is the graph useful in analyzing the data?" Here, the students had basic answers for me. (..."So you don't mess up".)I think as we continue to use this method though, students will realize what an asset this is.
To summarize with students, I have them write the following in their notes. While the students are writing they were continuing to analyze the information. One student remarks that her cat weighs more than this dog! The students work with their table partner to model the steps, just as I had done earlier in the lesson.
Niki weighed 4 pounds when Layla brought him home. Niki weighed 14 pounds when she was 4 years old. Her greatest weight was 20 pounds at 8 years old.