A) The student will represent data in scatterplots.
B) The student will make observations about data represented in scatterplots.
C) The student will use a drawing to estimate the line of best fit for data represented in a scatterplot.
A scatterplot is a way of graphing individual points between 2 variables (e.g., height & weight) on a coordinate plane. One of these variables goes horizontally (sideways) along the x-axis, and the other one goes vertically (up & down) along the y-axis. It doesn't matter which variable goes on which axis.
The only time it would matter which variable goes on each axis is if they are independent & dependent variables.
Pay attention to the pattern of the points on a scatterplot. If there is a patter, there may be a line of best fit: a line that predicts the trend of the graph. You can use the line of best fit for interpretations and predictions.
If you're graphing a line of best fit, try to make it so that half of the points are above the line and half are below the line.
The line of best fit is only used to predict where the points will be graphed. It's possible that there will be outliers, or points that occur away from the trend.
When looking for a pattern on the graph, you'll be looking for 4 things:
Do the points tend to go up & right?
Do the points tend to go down & right?
Do the points tend to be flat?
Are they all over the place?
These observations will tell us if there is a correlation (a relationship / connection) between the 2 variables. This is also known as "trending" in a certain direction. For example: do kids tend to weigh more as they grow taller?
If the data points trend (go) up & right, this is a positive correlation -- meaning that both variables go up at the same time or down at the same time (e.g., kids weigh more as they grow taller).
If the data points trend (go) down & right, this is a negative correlation -- meaning that one variable increases while the other one decreases (e.g., battery life goes down when you use your phone more).
If the data points trend (go) flat or they are all over the place, this is known as no correlation -- there is no connection between the variables (e.g., how many siblings you have and how tall you are).
Important: Just because there is a connection between 2 variables does not automatically mean that one of them causes the other one.
Example: People carry umbrellas when it rains, but the weather doesn't take control of their brains and make them carry umbrellas -- they just prefer to be dry than wet & cold.
Collect, organize, and represent a data set of no more than 20 items using scatterplots. (a)
Make observations about a set of data points in a scatterplot as having a positive linear relationship, a negative linear relationship, or no relationship. (b)
Estimate the line of best fit with a drawing for data represented in a scatterplot. (c)
No tips on this one; just look at the graph. :)
7.BB.17-18
8.CC.15-17
A.KK.8-9, 12
Math Snacks
Creature Caverns (plotting points on a graph)
Game Over, Gopher (plotting point on a graph)