In today's lesson, we discuss line graphs. To begin the lesson, I call the students to the carpet to watch a Brainpop video at the following website: http://www.brainpopjr.com/math/data/linegraphs/
Upon the completion of watching the video, the students return to their seats. I discuss with the students the information learned from the video. I remind the studenst that the video said that we graph information on a line graph to track how things have changed over a period of time. The video told us about the "x" axis which is the horizontal axis. (I draw a horizontal line on the board to give the students a visual.) The video also told you about the "y" axis, which is the vertical axis. (Again, this is demonstrated on the board.)
Just as with the line plots that you learned about yesterday, we can answer questions from the data on a line graph. A line graph gives us a visual and makes it easier to see what the numbers mean. I give the students an example of why it is important to learn about line graphs. I tell the students that sometimes our jobs will require us to do reports for our bosses. We may have some data that we want to share in a meeting. A lot of times the bosses or managers want to see the information in a graph because it is easier to read in this format. If I'm telling you that prices went up one month, and then the prices went down, I can show this trend in a line graph because you will be able to see the line going up, then down.
On the Smartboard, I display the Teaching Tool - Line Graphs. In this particular table, we are talking about the average high temperatures in Tennessee. I actually collected data about our state. We have our months, 1 - 12, January through December. I discuss the temperatures in the table with the students. As we discuss each temperature, I point out that information as it is plotted on the line graph. I remind the students that the BrainPop told us that we need to pay attention to the intervals on the graph. I ask the students to tell me the intervals on the 'Temperature in Tennessee' graph. The students knew that the numbers on the graph were in intervals of 10. I let the students know that they need to pay careful attention to this because they will have to come up with their intervals for their line graphs. I tell the students to be sure to give their graphs a title, and label the "x" axis and the "y" axis.
From the data in the line graph, I ask the students questions:
Which month had the highest temperature? Student response: July, 89 degrees
Which month had the lowest temperature? Student response: January, 46 degrees
I tell the students that we can look at a graph and see the "trend". We can see if there is an increase or a decrease, or if it stays the same. What is the trend at the beginning of the year? Student response: The temperature is rising. I let the students know that they are correct. The temperatures at the beginning of the year were increasing. I point out that in July we had our highest average temperature. I ask, What happened to the temperatures after July? Student response: decreasing. I wonder why it started decreasing after July? To get them to really think, I ask, What's going on at this time of year? Student response: it is getting colder because of the seasons.
For this activity, I let the students work independently to collect data for a line plot.
I give each student a Line Graph Activity, a piece of graph paper, a ruler, and a crayon. The students must take the information in the table and graph it in a line graph. The students must determine the intervals for the data. Because these are such large numbers, I give the students help with determining the starting number and the last number for the "y" axis. I do this by questionging the students. I ask the following questions to guide them to the correct numbers to put on the line graph:
1. What is the lowest number in your data set?
2. What is the highest number in your data set?
3. What is the smallest number you can include on your graph?
4. What is the highest number you should include on your graph?
5. What intervals can you use to cover all of these numbers?
After we have determined the correct numbers to use on the graph, the students work independently to graph the information. As the students work, I walk around to monitor and assist students as needed. Any misconceptions are addressed at this point, as well as whole class at the end of the activity.
To close the lesson, I bring the students back together as a whole class. I feel that it is very important to let the students share their answers as a whole class. This gives those students who still do not understand another opportunity to learn it.
I feel that by closing each of my lessons by having students share their work is very important to the success of the lesson. Students need to see good work samples (Student Work - Line Graphs), as well as work that may have incorrect information. More than one student may have had the same misconception. In this particular lesson, as a whole class, we discussed how to determine the intervals for the line graph. Also, we discussed beginning the "y axis" with zero. In the Video for Line Graphs, you will see a sample of student work. It shows that the student understood the skill, but still has to work on accuracy.