Graphing and Tally Marks
Lessons in this chapter
About Graphing and Tally Marks
Data Detective moves a 2nd grader from reading other people’s data to collecting their own.
Collect and Organize Data using Tally Marks is the new part. 1st grade read tally charts that already existed; here kids gather the data themselves, which means deciding what the categories are before counting anything. Choosing categories that do not overlap is a real decision and the first piece of statistical thinking.
Read and Interpret Picture Graphs and Read and Interpret Bar Graphs return to familiar formats with harder questions and scales where one unit stands for more than one item. Misreading the key stays the most common error.
Read and Interpret Line Plots is the new format. A line plot puts marks above a number line, which means the horizontal axis is a scale rather than a set of categories, and that makes it the first graph where the spread of the data is visible rather than just the totals.
Collect and Organize Data using Tally Marks, Read and Interpret Picture Graphs and Read and Interpret Bar Graphs each open as a worksheet in the page, marked as your child answers. The questions are the point: not which bar is tallest, but how many more one category has than another. Four lessons, all free to practice online.
Frequently asked questions
Collecting and organizing data with tally marks, and then reading and interpreting picture graphs, bar graphs and line plots. Making the data first is what makes reading someone else's graph make sense. It sits in Measurement and Data (2.MD), where the 2nd grade standards cover picture graphs, bar graphs and line plots.
Collecting and organizing data with tally marks, and reading and interpreting picture graphs, bar graphs and line plots.
A graph with marks stacked above a number line. Because the axis is a scale rather than a list of categories, it shows how the data is spread, not just how much of each there is.
1st grade read data that already existed. Here kids collect their own, which means choosing categories before counting, and line plots are added.
Because categories that overlap or leave gaps make the data unusable. Deciding them before counting is the first genuinely statistical decision kids make.
What each gridline is worth. If the scale goes up in twos, a bar reaching the fourth line means eight, not four, and reading it as four is the usual mistake.