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Lesson plan Grade 3 Science

Birch Grove's Rain Gauge: A Grade 3 Water Cycle Graphing Lesson

A 45-minute grade 3 lesson where students graph four weeks of a fictional school rain gauge's readings on a scaled bar graph and connect the totals to the water cycle.

Objectives

  1. Students will build a scaled bar graph from four weeks of rain gauge data collected at a fictional school.
  2. Students will explain how the amount of rain a gauge measures connects to the stages of the water cycle.
  3. Students will use their completed bar graph to answer how-many-more and how-many-less questions.

Vocabulary

Evaporation
Evaporation happens when liquid water, often warmed by the sun, turns into an invisible gas called water vapor that rises into the air. It is how water leaves oceans, lakes, and puddles.
Condensation
Condensation is when water vapor in the air cools down and turns back into tiny liquid water droplets. It is how clouds form and why a cold glass gets wet on the outside on a warm day.
Precipitation
Precipitation is any water that falls from clouds to the ground, including rain, snow, sleet, and hail. It is the main way water returns from the sky to the surface of the Earth.

Also: rain gauge, scaled bar graph, collection

Teacher overview

Birch Grove Elementary, a fictional school used for this lesson, keeps a rain gauge outside its classroom window and records how many centimeters of rain fall each week. This lesson uses four weeks of that gauge's readings to give students a concrete dataset to graph, then ties the totals back to the water cycle: rain that lands in the gauge started as water vapor that evaporated somewhere else, cooled into clouds through condensation, and fell back down as precipitation before collecting in the gauge. A common misconception in this lesson is that the number of squares in a bar is the number of centimeters of rain. That holds only when each square on the graph stands for one centimeter; when each square stands for more than one centimeter, as it does here, students must multiply the number of squares by the scale to read the amount, and this lesson is built to catch that error directly.

Procedure

Hook (5 min): Show students a drawing or photo of a simple rain gauge, a container marked with a measuring scale that catches falling rain. Ask: "If it rains a lot one week and only a little the next, how could we keep track and compare?" Take a few guesses without commenting on which is best, then explain that Birch Grove Elementary keeps exactly this kind of gauge outside its classroom.

Direct instruction (10 min): Write the four weeks of gauge data on the board: Week 1: 4 cm, Week 2: 8 cm, Week 3: 2 cm, Week 4: 6 cm. Review the four water cycle stages the rain gauge connects to: evaporation (water rising into the air as vapor), condensation (vapor cooling into clouds), precipitation (water falling as rain), and collection (rain gathering in the gauge, the ground, and streams). Model drawing the first bar of a scaled bar graph on graph paper, explaining that each square on the grid stands for 2 centimeters of rain, not 1, because a scale lets a graph show larger amounts in less space, and reading a scale is the skill this lesson practices. Show that Week 1's 4 cm bar is 2 squares tall (4 ÷ 2 = 2).

Guided practice (15 min): In pairs, students plot the remaining three weeks' bars on their own graph paper, using the same 2-centimeters-per-square scale, and label each bar with its week number. Circulate and check that partners are dividing by the scale correctly before drawing (a bar for 6 cm should be 3 squares tall, not 6 squares tall).

Independent practice (10 min): Each student answers three questions on the handout using their completed graph: (1) which week had the most rain, which had the least, and how many centimeters separate them; (2) how many total centimeters of rain fell across all four weeks; (3) how many more centimeters fell in Week 2 than in Week 4.

Closure / exit ticket (5 min): On an index card, students answer: "A fifth week is added to the gauge and it measures 10 cm of rain. How many squares tall would that new bar be on our graph?" Collect the cards and scan for the correct scale reasoning (dividing by 2) before dismissal.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key
  1. Answer: Week 2 had the most rain (8 cm) and Week 3 had the least (2 cm); they are separated by 6 cm. 8 − 2 = 6.
  2. Answer: 20 cm total. 4 + 8 + 2 + 6 = 20.
  3. Answer: 2 cm more. Week 2 (8 cm) − Week 4 (6 cm) = 2.
  4. Exit ticket answer: 5 squares tall. 10 cm ÷ 2 cm per square = 5 squares.

Differentiation

Support (below grade level)

Provide graph paper with the vertical axis already labeled in the 2-centimeters-per-square scale, so students only need to count and shade the correct number of squares rather than also drawing the axis. Reduce independent practice to two of the three questions, and allow a hundred chart for the subtraction steps.

Extension (above grade level)

Ask students to consider what would happen if a fifth week's rainfall were 20 cm, more than twice the current highest week (8 cm). Have them redraw the graph using a new scale of 4 centimeters per square instead of 2, then explain in writing how changing the scale changes the height of every bar even though the actual rainfall amounts stay the same.

ELL supports

Pre-teach "gauge," "scale," "evaporation," "condensation," "precipitation," and "collection" using simple picture cards that show each stage of the water cycle in sequence. Provide a sentence frame for the exit ticket: "The bar would be ___ squares tall because 10 divided by 2 equals ___."

Extensions

If your classroom has an outdoor space, set up a real rain gauge and keep a running weekly log for a month, then compare the real totals to the four weeks used in this lesson. A real week's rainfall will often differ from students' predictions, which opens a natural discussion about why weather is hard to predict exactly.