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Lesson plan Grade 5 Math

Copperfield Rain Garden: A Grade 5 Fraction Multiplication Lesson

A 45-minute grade 5 lesson where students multiply fractions by whole numbers and by fractions to measure rain captured by a fictional school rain garden.

Objectives

  1. Students will multiply a fraction by a whole number to find a total amount.
  2. Students will multiply a fraction by a fraction and explain the smaller result.

Vocabulary

Rain garden
A rain garden is a shallow planted dip in the ground that catches rain running off a roof or driveway and lets it soak slowly into the soil. Its deep-rooted plants help clean the water.

Also: fraction, multiply, product

Teacher overview

Copperfield Elementary is a fictional school with a rain garden that catches rain after a storm. Each garden bed soaks up a fraction of the rain, and each rain barrel fills a fraction of a gallon each minute. Those settings let students multiply a fraction by a whole number and a fraction by a fraction. A common student error is thinking that multiplying always makes a number bigger, so the lesson makes a point of showing that multiplying by a fraction less than 1 gives a smaller result.

Procedure

Hook (5 min): Ask students what happens to rain that lands on the school field after a big storm. Guide them to the idea that a rain garden holds some of that water instead of letting it run off. Show a photo or sketch of a garden bed.

Direct instruction (12 min): Model 3/4 gallon per minute times 5 minutes by drawing five groups of 3/4 and combining them into 15/4, then rename it as 3 3/4 gallons. Next, model 1/2 of 3/4 inch with an area model of a rectangle split both ways, showing the product 3/8. State the pattern: a fraction times a whole number scales the whole number, and a fraction times a fraction is the overlap of the two shaded parts of a rectangle.

Guided practice (10 min): Work handout items 1 and 3 with the class, one of each type, drawing the model each time. Ask a check question after each.

Formative check (5 min): Ask students to answer on a whiteboard: "Is 1/2 of 3/4 more or less than 3/4?" Look for "less." If several students say "more," redraw the area model before moving on.

Independent practice (8 min): Students finish the handout on their own while you circulate and check the drawings.

Closure and exit ticket (5 min): Students answer on a card: "A bed soaks up 1/2 of 1/2 inch of rain. How much is that?" Collect and scan for 1/4 inch before dismissal.

Copperfield Rain Garden: A Grade 5 Fraction Multiplication Lesson — Grade 5 Math
Name: ____________________________ Date: ______________

Student Handout

Solve each problem. Draw a model to show your thinking.

  1. A rain barrel fills 3/4 gallon each minute. How much water fills in 5 minutes?
  2. Six barrels each fill to 2/3 of a 30-gallon mark. How many gallons is 2/3 of 30?
  3. A garden bed soaks up 1/2 of a 3/4-inch rainfall. How many inches does the bed soak up?
  4. Four beds each capture 5/8 gallon of runoff. How many gallons do the four beds capture in all?
  5. Multiply 2/3 by 1/4. What is the product?
  6. Explain in one or two sentences why multiplying 3/4 by 1/2 gives an answer smaller than 3/4.

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: 3 3/4 gallons. 3/4 x 5 = 15/4, which is 3 3/4 gallons.
  2. Answer: 20 gallons. 2/3 x 30 = 60/3 = 20 gallons.
  3. Answer: 3/8 inch. 1/2 x 3/4 = 3/8 inch.
  4. Answer: 2 1/2 gallons. 4 x 5/8 = 20/8, which is 2 1/2 gallons.
  5. Answer: 1/6. 2/3 x 1/4 = 2/12, which simplifies to 1/6.
  6. Answer: Multiplying 3/4 by 1/2 gives a smaller answer because you are taking only half of the 3/4, and half of an amount is less than the whole amount.
  7. Exit ticket answer: 1/4 inch. 1/2 x 1/2 = 1/4 inch.

Differentiation

Support

Provide pre-drawn area-model rectangles so students only shade the parts for each problem. Keep the guided examples on display during independent work, and allow a multiplication chart.

Extension

Ask students to find how much water 8 barrels fill in 10 minutes at 3/4 gallon per minute each, and to explain the order they multiplied the numbers.

ELL supports

Pre-teach "soak up," "capture," "product," and "runoff" with a simple picture of rain landing on a garden. Provide a sentence frame for item 6: "The answer is smaller because ___."