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Classroom activity Grade 3 Math

Quail Run Garden's Sprinkler Arrays: A Multiplication Station Activity

A grade 3 station-rotation activity where students build counter arrays for four community garden plots and write multiplication equations for gallons per minute.

Objectives

  1. Students will build an array to represent equal groups of sprinkler heads and gallons per minute.
  2. Students will write a multiplication equation matching a garden plot's total water use.
  3. Students will compare two arrays with the same product but different factors.

Vocabulary

Key words: array, equal groups, factor, product

Teacher overview

At the fictional Quail Run Community Garden, four plots are each watered by a set of sprinkler heads that spray the same number of gallons per minute. This is a station-rotation activity for small groups of 4 to 6 students: each of the four stations represents one plot, and a sign tells the group how many sprinkler heads that plot has and how many gallons per minute each head sprays. Groups build the matching array with counters, count the total, and write the multiplication equation for that plot's total water use. A common misconception this activity addresses directly is that a different-looking array (different rows and columns) must have a different total; two of the four plots here share the same total gallons per minute despite having different array shapes.

Activity Directions

  1. Before class, set up four stations around the room, each with a grid mat and a sign. The signs read: Station 1, Tomato Bed: 3 sprinkler heads, 4 gallons per minute each. Station 2, Bean Rows: 4 sprinkler heads, 5 gallons per minute each. Station 3, Herb Spiral: 6 sprinkler heads, 2 gallons per minute each. Station 4, Pumpkin Patch: 5 sprinkler heads, 5 gallons per minute each.

  2. Explain how the activity works to the whole class: each row of counters on the grid mat represents one sprinkler head, and each counter in that row represents 1 gallon per minute that head sprays. Building the full array and counting every counter gives the plot's total gallons per minute.

  3. Divide the class into four groups of 4 to 6 students. Send one group to each station.

  4. At each station (7 minutes), the group builds the array on the grid mat: one row of counters for each sprinkler head listed on the sign, with the stated number of counters (gallons) in each row. The group counts the total counters, writes the multiplication equation (heads × gallons per head = total gallons per minute) on their recording sheet, and records the total.

  5. When the timer sounds, groups clear their grid mat and rotate to the next station in order (Station 1 to 2, 2 to 3, 3 to 4, 4 back to 1).

  6. Repeat step 4 at each new station until every group has completed all four stations (four rounds of 7 minutes each).

  7. End the rotation once every group has recorded a total for all four plots. Gather the class for the debrief, comparing recorded totals across groups to confirm everyone found the same four totals.

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: 12 gal/min.
    Tomato Bed: 3 sprinkler heads × 4 gallons per minute each = 12 gallons per minute.

  2. Answer: 20 gal/min.
    Bean Rows: 4 sprinkler heads × 5 gallons per minute each = 20 gallons per minute.

  3. Answer: 12 gal/min.
    Herb Spiral: 6 sprinkler heads × 2 gallons per minute each = 12 gallons per minute.

  4. Answer: 25 gal/min.
    Pumpkin Patch: 5 sprinkler heads × 5 gallons per minute each = 25 gallons per minute.

  5. Debrief question: "The Tomato Bed (3 × 4) and the Herb Spiral (6 × 2) both total 12 gallons per minute. What does this tell us about multiplication?" Answer: Different pairs of factors can give the same product; 3 groups of 4 and 6 groups of 2 both equal 12, even though the arrays have a different number of rows and columns.

  6. Debrief question: "Which plot uses the most water per minute, and how can you tell from its array?" Answer: The Pumpkin Patch, because its array (5 rows of 5 counters) has the most total counters of the four plots, 25 gallons per minute.

Differentiation

Support (below grade level)

Provide station signs with the array already outlined in dashed boxes on the grid mat, so students place one counter in each box rather than deciding the layout themselves. Allow students to count the total by ones instead of requiring the multiplication equation before checking their work.

Extension (above grade level)

Ask students to design a fifth plot that would also total 20 gallons per minute (like Bean Rows) using a different number of sprinkler heads, build that array, and write its multiplication equation.

ELL supports

Pre-teach "sprinkler head," "row," and "total" using a simple picture card showing one row of a garden array labeled with all three words. Allow groups to point to and count counters aloud together rather than requiring one student to explain the equation alone.