One-to-One and Many-to-One Correspondence in Graphs
Warm-up
Show two bar graphs of the same data with different scales. Graph A: scale 1=1, bars reach 20+ squares. Graph B: scale 1=5, bars reach 4 squares. Both correct. Which is easier to read? Why? When would you choose a larger scale? (When data values are large.)
Explore
Scale selection and graph creation: each group receives a data set with values between 20 and 80. They must (1) choose an appropriate scale, (2) build the graph, (3) verify the scale works for all values. Compare: did different groups choose different scales? Are both valid?
Consolidate
Practice
Students create one bar graph and one pictograph for the same data set using chosen scales, then critically evaluate 2 provided graphs for potential misrepresentation. Exit ticket: a bar graph has scale 1=10. A bar is 7 units tall. What value does it represent?
Exit ticket
Students create one bar graph and one pictograph for the same data set using chosen scales, then critically evaluate 2 provided graphs for potential misrepresentation. Exit ticket: a bar graph has scale 1=10. A bar is 7 units tall. What value does it represent?
2.5 x 4 = 10 people.
Largest value is 50. Scale 1=5: bars reach 10, 7, 4, and 9 squares. Clean and readable. Scale 1=10 would give a bar of 5, 2, and 4.5 squares (half bars for 35 and 45). Scale 1=5 is better.