Grade 4 Data Science
When two different groups answer the same question, how can we show the comparison clearly — and what can we learn from the difference?
Two fourth-grade classes were asked: "What is your favorite pet?"
Class A has 28 students. Class B has 34 students.
Both classes got to pick from: Dog · Cat · Fish · Bird · Other
→ Turn and talk: If we put these results into a single chart, what would it look like?
A double bar chart shows the same categories for two different groups side by side. Each category has two bars — one per group. A legend tells you which color belongs to which group.
• The two bars for the same category must be right next to each other
• Leave a gap between different categories
• Always start Y-axis at zero — starting higher makes differences look bigger than they are
• The legend must match the exact colors you used
→ What do you notice? What surprises you?
Class A and Class B have opposite top choices: Class A loves dogs most, Class B loves cats most. This is called a reversal — the groups rank the same options differently.
Use the data table on your worksheet to build a double bar chart for Class A and Class B pet preferences.
① Draw and label axes (X = pet, Y = number of students, 0–14)
② Draw Class A bars in dark blue
③ Draw Class B bars in light blue / teal
④ Add a legend and a title
⑤ Use a ruler — bars should be neat and even width
Draw all Class A bars first, then go back and add all Class B bars. That way you won't mix up which bar belongs to which group.
Use these frames to write about your chart:
Here are three complete sentences written from the pet preference chart. Study the structure.
"Class A preferred dogs more than Class B — 12 students vs. 8 students."
"Class A had the most dog fans, while Class B had the most cat fans — showing the classes have opposite top choices."
"The smallest difference was for Bird — Class A had 3 students and Class B had 5, just 2 apart."
→ Notice: each sentence names the pet, states both numbers, and uses a comparison word.
Using your chart and the sentence frames on the board, write 3 comparison statements about the pet data. Each sentence must:
✓ Name the specific pet category
✓ Include the actual numbers from the chart
✓ Use a comparison word: more than · less than · both · while · biggest · smallest
Can you write one sentence that talks about the total difference across all categories combined? (Hint: add up all Class A numbers and all Class B numbers.)
Class A has 28 students. Class B has 34 students.
When Class B has 11 cat fans and Class A has 7 cat fans, is Class B really that much more into cats — or is it just because Class B is bigger?
If you combined both classes into one group, which pet would be most popular overall? Work it out with your partner. (Dog: 12+8=20 · Cat: 7+11=18 · Fish: 4+6=10 · Bird: 3+5=8 · Other: 2+4=6)
What might explain why Class A loves dogs more and Class B loves cats more? What information would you want to collect to find out?
A student says "double bar charts are just two charts stuck together." Is that correct? What can a double bar chart show that two separate charts cannot?
I'll call out a category. Stand up if Class A is higher. Stay seated if Class B is higher.
Dog… (stand — Class A wins 12 vs 8)
Cat… (sit — Class B wins 11 vs 7)
Fish… (sit — Class B wins 6 vs 4)
Bird… (sit — Class B wins 5 vs 3)
Other… (sit — Class B wins 4 vs 2)
Result: Class A only wins for one category (Dog). Class B is higher in all others!
Next session is your Data Story Capstone! You'll collect your own data, organize it, build a chart, and write a complete data story. Start thinking about a question you'd like to investigate.
Write one sentence comparing the two classes for any pet category. Your sentence must include both numbers and one comparison word.
Grade 4 Data Science · Session 7 · sdabagh.github.io