Lesson plan Grade 3 Health & Consumer Science
The Quimby Family's Water Glasses: A Scaled Bar Graph Lesson
A 45-minute grade 3 lesson where students graph how many glasses of water a fictional family drank in a day and solve how-many-more problems from the scaled bars.
Objectives
- Students will draw a scaled bar graph in which one square stands for two glasses of water.
- Students will solve one-step and two-step comparison problems using the bars on a scaled graph.
Vocabulary
Key words: bar graph, scale, data, compare
Teacher overview
The fictional Quimby family spent one Saturday counting every glass of water each person drank, and their tally gives this lesson its data set. Graphing that tally lets students practice the grade 3 scaled bar graph standard on a health topic they can repeat at home with their own families. The central misconception this lesson targets is reading the number of squares as the number of glasses: with a scale of two glasses per square, a bar three squares tall shows six glasses, not three, and the procedure returns to that point twice. Draw the empty class graph on chart paper before the lesson starts.
Procedure
Hook (5 min): Ask students to think about how many glasses of water they drank yesterday and hold up fingers. Read a few of the counts aloud and note the range you see. Explain that one family, the Quimbys, counted a whole Saturday, and that the class will turn those counts into a graph so the amounts can be compared side by side.
Direct instruction (10 min): Post the data on the board: Mom 8 glasses, Dad 2 glasses, Ada 6 glasses, Theo 4 glasses. Tell the class the graph will use a scale where one square stands for 2 glasses. Model drawing Mom's bar: count by twos while shading four squares, saying "two, four, six, eight." Ask the class why the bar is four squares tall when Mom drank eight glasses, and let a student state the scale rule in their own words.
Guided practice (15 min): Students draw the remaining three bars on grid paper while you build the same bars on the chart paper graph. After each bar, ask a scale question: how many squares for Dad's 2 glasses, for Ada's 6, for Theo's 4? Check for understanding with a quick poll after Theo's bar: hold up the number of squares Theo's bar needs. If hands show anything other than two fingers, re-model counting by twos before continuing.
Independent practice (10 min): Students answer handout questions 1 through 4 using their finished graphs. Remind them that the questions ask about glasses, so they must use the scale, not just count squares.
Closure and exit ticket (5 min): Students answer handout question 5 on the bottom strip, tear it off, and hand it in. The strip shows quickly who still confuses squares with glasses.
Student Handout
The Quimby family counted glasses of water on Saturday. Imagine you are checking their graph. Here is the data: Mom drank 8 glasses, Dad drank 2 glasses, Ada drank 6 glasses, and Theo drank 4 glasses. On the graph, one square stands for 2 glasses.
- How many glasses of water did Mom drink on Saturday?
- How many more glasses did Ada drink than Theo?
- How many glasses did the whole family drink in all?
- Mom and Ada together drank how many more glasses than Dad and Theo together?
- Exit ticket: One square on the graph stands for 2 glasses. How many squares tall is Ada's bar?
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Answer Key
- Answer: 8 glasses. The data list and the tallest bar both show Mom at 8.
- Answer: 2 glasses. Ada drank 6 and Theo drank 4, and 6 - 4 = 2.
- Answer: 20 glasses. 8 + 2 + 6 + 4 = 20 glasses for the whole family.
- Answer: 8 glasses. Mom and Ada drank 8 + 6 = 14, Dad and Theo drank 2 + 4 = 6, and 14 - 6 = 8.
- Answer: 3 squares. Ada drank 6 glasses, and 6 divided by 2 glasses per square is 3 squares.
Differentiation
Support
Give students a graph with Mom's and Dad's bars already drawn so they only add Ada's and Theo's. Provide a counting-by-twos number line taped to the desk, and reduce the handout to questions 1, 2, and 5.
Extension
Have students redraw the same data with a scale of one square for 4 glasses, then write two sentences about what changed and what stayed the same. Ask whether question 5 would have a different answer on the new graph and why.
ELL supports
Pre-teach "scale," "bar," and "data" by building one bar with linking cubes, two cubes at a time. Post the sentence frame "___ drank ___ more glasses than ___" for questions 2 and 4, and let students say each answer to a partner before writing it.
Extensions
Send home a blank tally sheet so students can count their own family's Saturday glasses. The next week, students graph their family data with the same two-glass scale and compare their graph with the Quimbys' graph in a short paragraph.