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Lesson plan Grade 4 Engineering & Design

Rain Barrels for the Robin Lane School Garden: A Sizing Plan

A grade 4 engineering lesson where students use whole-number multiplication and division to size a rain barrel plan for a fictional school garden.

Objectives

  1. Students will multiply and divide whole numbers to find how much water a set of rain barrels can store and supply.
  2. Students will define a garden watering plan using a storage goal and the constraint of a fixed barrel size.
  3. Students will interpret a remainder as leftover gallons that do not fill a whole barrel.

Vocabulary

Rain barrel
A rain barrel is a container that catches rainwater from a roof downspout so it can be used later to water plants. It saves drinking water and keeps some runoff out of the storm drains.

Also: store, conservation, remainder

Teacher overview

The garden club at the fictional Robin Lane School wants to water its vegetable beds with rain it collects in barrels instead of the hose. This lesson has students size that plan with grade 4 multiplication and division: how much water the barrels hold, how many waterings that gives, and how many barrels the club needs to reach its goal. A common misconception this lesson addresses: students reach for multiplication whenever a problem names two numbers, even when the question asks how many equal groups a stored amount makes, so the procedure models reading the question for its unit, gallons or waterings, before choosing an operation. Each handout problem states the numbers it needs in its own text.

Procedure

Hook (5 min): Tell the class the garden club's goal in plain words: collect enough rain in barrels to water the garden without the hose. Ask, "If one barrel holds 60 gallons, how much would three barrels hold?" Take a few answers and model the multiplication 60 x 3 = 180 gallons on the board, telling students they will meet this same barrel size again on the handout.

Direct instruction (10 min): Introduce the plan's key facts as a labeled list: a barrel's size, how much one watering uses, and how often the garden is watered. Model a single worked example with numbers not used on the handout: if the club had 120 gallons stored and one watering uses 40 gallons, then 120 / 40 = 3 waterings. Show how the answer's unit (waterings) comes from the words in the problem.

Guided practice (15 min): Hand out the student page. In pairs, students work problems 1 and 2 together, checking that each answer carries the right unit (gallons or waterings). Pause the class to compare answers to problem 2 before moving on, so everyone starts the independent set with a correct value.

Independent practice (15 min): Students finish problems 3 through 6 on their own, showing each step. Remind them that problem 6 will have gallons left over that do not fill a whole barrel, and that the leftover is part of the answer.

Closure / exit ticket (5 min): For a formative check, students answer this on the back of the handout without turning back to problem 2: "The club stores 240 gallons and one watering uses 30 gallons. Write the number sentence you would use to find how many full waterings that is, and name the unit the answer carries." Collect and scan for a division of 240 by 30 with the answer labeled in waterings before dismissal.

Rain Barrels for the Robin Lane School Garden: A Sizing Plan — Grade 4 Engineering & Design
Name: ____________________________ Date: ______________

Student Handout

Suppose the Robin Lane garden club is planning its rain barrels. Each problem tells you the numbers you need. Show your work and label each answer.

  1. One rain barrel holds 60 gallons. The club sets up 4 barrels. How many gallons can the club store when all 4 barrels are full?
  2. Watering the whole garden one time uses 30 gallons. The club has 240 gallons stored. How many full waterings is that?
  3. The club waters the garden 2 times each week. The stored water is enough for 8 waterings. For how many weeks will the stored water last?
  4. A big storm fills 3 empty barrels. Each barrel holds 60 gallons. How many gallons did the storm collect?
  5. The club wants to store at least 300 gallons. Each barrel holds 60 gallons. How many barrels does the club need to reach that goal?
  6. The club collected 250 gallons of rain. They pour it into empty 60-gallon barrels. How many barrels do they fill all the way, and how many gallons are left over?

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: 240 gallons. Multiply the barrels by the size of each barrel: 60 x 4 = 240 gallons.
  2. Answer: 8 waterings. Divide the stored water by one watering: 240 / 30 = 8 waterings.
  3. Answer: 4 weeks. Divide the waterings by how many happen each week: 8 / 2 = 4 weeks.
  4. Answer: 180 gallons. Multiply the barrels the storm filled by their size: 60 x 3 = 180 gallons.
  5. Answer: 5 barrels. Count barrels of 60 gallons up to the goal: 60 x 5 = 300 gallons, so 5 barrels reach 300 gallons.
  6. Answer: 4 barrels, with 10 gallons left over. 250 / 60 = 4 with a remainder of 10, so 4 barrels fill all the way (60 x 4 = 240 gallons) and 10 gallons are left, not enough to fill a fifth barrel.

Differentiation

Support

Give students a labeled picture of one 60-gallon barrel and let them draw barrels to model problems 1 and 4 before multiplying. Provide a multiplication chart, and start pairs on problems 1 and 4, which use only multiplication, before the division items.

Extension

Ask students to plan for a bigger garden that needs 45 gallons per watering. Have them find how many full waterings 240 stored gallons would give, interpret the leftover gallons, and explain how the larger watering amount changes the answer compared with problem 2.

ELL supports

Provide a word bank with "barrel," "store," "watering," and "left over," each next to a small picture. Give a sentence frame for the answers: "The club can ___ because ___." Allow students to show division as equal groups drawn on paper rather than as a written number sentence.