Graphing Using a Frequency Table
Lesson 2 of 4
Objective: SWBAT summarize a data set with multiple categories using a frequency table, dot plot and bar graph with scaled intervals.
Who can help me with this definition of frequency?
This is the definition that I've posted on the Board:
The frequency of a particular data value is the number of times the data value occurs.
Why would we want to understand how often something occurs?
Something that you guys know a lot about is graphing, but something we haven’t done before is create 2 different graphs to represent the same exact information. Sometimes, one graph may be easier to read, or easier to create than another so it’s important we have options when graph data.
I need a partner to roll the dice for me, and whatever number it falls on I will tally it here. I need to collect some data so that I can use it for my graphing today.
We roll the dice a few times and then I show students an example of a completed frequency table.
Today you are your partner are going to take turns rolling the dice and tallying what you roll. You’re going to need to record nice and neat because you’ll need the data to complete your frequency table and your frequency table is what you will use to make your different graphs for today.
I stop here to review both kinds of graphs and discuss the importance of making my intervals reasonable.
Students still struggle at times to make their intervals reasonable, based on the data set they have (i.e., their intervals go by 5’s but their actual data is more easily represented by intervals of 2).
Students will work in partners to create a frequency chart using their dice rolls. Next, they create a bar graph and a line plot of this data.
Students need to ensure their intervals are reasonable, their graphs match and both their work and their partner's work is aligned since they are deriving their data from the same frequency table.
I feel it is important to emphasize to students that there is no "right" answer, and that the way I would set up my graph is not necessarily the same way they might choose to- which you will hear in the video. There are many ways that students could have set up their graphs, set up their intervals or set up their bars and lines. The emphasis is not on setting things up my way, but that students feel confident to make choices about their math and that they have reasons and can justify the choices they make.
Who can tell me what you learned today about frequency tables?
Why is it important as mat experts to know how to represent data multiple ways?
And why is it important to select reasonable intervals for our graphs?