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Lesson plan Grade 4 Science

Watering the Bordray School Orchard From One Rain Barrel

A grade 4 lesson where students set criteria for a fictional school orchard's watering plan, then multiply and divide to test whether one rain barrel is enough.

Objectives

  1. Students will state the criteria and the constraints of a school orchard's summer watering problem.
  2. Students will multiply and divide whole numbers to compare a rain barrel's supply with the orchard's weekly need.
  3. Students will interpret a remainder as an extra bucket trip instead of dropping it.

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: criteria, constraint, irrigation, remainder

Teacher overview

Bordray Elementary, a fictional school in a farming county, planted twelve young apple trees along its back fence and waters them from one 55-gallon rain barrel. Before students calculate anything, they write down what the watering plan has to accomplish and what limits it, which is the engineering habit of separating criteria from constraints. The arithmetic that follows is ordinary grade 4 multiplication and division, but it settles a real question: whether the barrel can carry the orchard through a dry June. A common error here is dropping the remainder. Students divide 27 gallons into 4-gallon buckets, get 6 with 3 gallons left, and answer six trips, which would leave three gallons sitting at the tap. Ask every student to say aloud what the leftover gallons stand for before they write the final answer.

Procedure

Hook (5 min): Show the class a 4-gallon bucket and tell them the back-fence orchard has twelve young trees. Ask how many bucket trips they think one full rain barrel could cover. Record three guesses on chart paper without correcting any of them.

Naming criteria and constraints (10 min): Explain that engineers write down two lists before they solve a problem. Criteria say what a good plan must do; constraints say what the plan cannot exceed. Build both lists with the class on chart paper for the Bordray orchard. Criteria: every tree gets its full weekly share, and no tree is skipped two weeks in a row. Constraints: one barrel, refilled only by rain; buckets carried by hand; four weeks in the plan. Keep this chart visible for the rest of the lesson.

Teacher-modeled example (10 min): Model the arithmetic with a smaller orchard that is not on the handout. A different school has 8 trees that each need 3 gallons a week, so the weekly need is 8 x 3 = 24 gallons. If a 30-gallon barrel is full, 30 - 24 = 6 gallons remain after one full watering. Show the division form as well: 30 divided by 3 gives 10 full shares, which is more shares than that orchard needs. Think aloud about which operation answers which question.

Handout, items 1 to 6 (15 min): Students work items 1 through 6 with a partner. Circulate and check that students label their answers with gallons or trees rather than leaving bare numbers. Stop the room after eight minutes for a quick check for understanding: ask for a thumbs up from every student who has a labeled answer for item 3, and reteach the subtraction step at the board if fewer than three quarters of the class signals yes.

Compare and discuss (5 min): Ask two pairs to read their answer to item 6 and explain how they knew the orchard would come up short in June. Return to the criteria chart and ask which criterion the barrel alone fails to meet.

Exit ticket, item 7 (5 min): Students answer item 7 alone on an index card and hand it in on the way out. Sort the cards into two piles as students leave: answers of 7 trips, and answers of 6 trips. The second pile tells you exactly who needs a remainder reteach tomorrow.

Watering the Bordray School Orchard From One Rain Barrel — Grade 4 Science
Name: ____________________________ Date: ______________

Student Handout

The Bordray Elementary orchard has 12 young apple trees. In a dry month each tree needs 4 gallons of water every week. The school's rain barrel holds 55 gallons when it is full. Suppose June has four weeks in this plan.

  1. The orchard has 12 trees. Each tree needs 4 gallons in one week. How many gallons does the whole orchard need in one week?

  2. A full barrel holds 55 gallons. Each tree takes 4 gallons. How many full 4-gallon shares does one full barrel hold?

  3. Start with a full 55-gallon barrel. All 12 trees each take 4 gallons. How many gallons are left in the barrel?

  4. The orchard needs 48 gallons each week. June has four weeks. How many gallons does the orchard need in all of June?

  5. Rain fills the 55-gallon barrel three times during June. How many gallons of rainwater does the orchard get that month?

  6. June needs 192 gallons. The barrel supplies 165 gallons. How many more gallons must the crew carry from the tap?

  7. The crew carries water in 4-gallon buckets. They must move 27 gallons from the tap to the orchard. How many bucket trips does that take?

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: 48 gallons.
    Twelve trees times 4 gallons each gives 12 x 4 = 48 gallons for one week.

  2. Answer: 13 shares.
    Divide the barrel among the shares: 55 divided by 4 gives 13 full shares with 3 gallons left over, which is enough for all 12 trees with one share to spare.

  3. Answer: 7 gallons.
    Twelve trees take 12 x 4 = 48 gallons, and 55 - 48 = 7 gallons stay in the barrel.

  4. Answer: 192 gallons.
    Four weeks at 48 gallons a week gives 4 x 48 = 192 gallons.

  5. Answer: 165 gallons.
    Three fills of 55 gallons give 3 x 55 = 165 gallons.

  6. Answer: 27 gallons.
    Subtract the supply from the need: 192 - 165 = 27 gallons.

  7. Answer: 7 trips.
    Dividing gives 27 divided by 4 equals 6 with 3 gallons left over. Six trips move only 24 gallons, so the crew needs a seventh trip for the last 3 gallons. Accept 6 full buckets and 1 partly full bucket as the same answer.

Differentiation

Support

Give these students a partially completed handout with item 1 already worked and labeled, and supply a printed row of twelve tree icons they can cross off in groups of four while they reason through item 2. Allow counters or base-ten blocks for the subtraction in items 3 and 6.

Extension

Ask students to design a second barrel plan that meets every criterion on the class chart. They must state the barrel size they would add, show the multiplication that proves the June total is covered, and explain what new constraint a second barrel introduces, such as where it would stand or who would carry the extra water.

ELL supports

Pre-teach criteria, constraint, and remainder with a two-column chart and a simple sketch of a barrel, a bucket, and a tree. Provide sentence frames for the discussion step: "The orchard needs ___ gallons because ___" and "The barrel is short by ___ gallons." Let students label their handout answers with a drawing of the bucket or the tree beside the number.

Extensions

Have the class measure the roof gutter above the barrel and sketch a scale drawing of where a second barrel could stand without blocking the walkway. Students can also keep a two-week rainfall log with a classroom rain gauge and compare the number of barrel fills their log predicts with the three fills used in this lesson.