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Lesson plan Grade 3 Math

Bellhaven School's Rain Barrel Gauge: A Grade 3 Unit Fraction Lesson

Students fold paper gauge strips into equal parts to read how full a fictional school's rain barrel is, naming unit fractions and building fractions from equal parts.

Objectives

  1. Students will name the unit fraction shown by one part of a strip folded into equal parts.
  2. Students will name a fraction as a count of equal parts, such as 3/8 as three parts of size 1/8.
  3. Students will compare 1/4 and 1/8 using two strips of the same length.

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: fraction, equal parts, unit fraction, gauge

Teacher overview

Bellhaven Elementary is a fictional school that catches roof runoff in a rain barrel beside the gym door, with a paper strip taped down the side so the class can see how full the barrel is. Because the strip is folded into equal parts rather than marked with numbers, reading it is a fraction task rather than a measuring task, which is what makes it useful this early in grade 3. The misconception the lesson corrects is naming a fraction from a part-to-part comparison: a student who shades 3 of 8 equal parts and sees 5 empty parts often writes 3/5 instead of 3/8. The exit ticket puts exactly that case in front of students so the teacher learns who still counts the empty parts into the denominator.

Procedure

Hook (5 min): Draw a barrel on the board with a plain strip down its side and ask how the class could tell, from across the playground, whether the barrel is nearly full. Take two or three answers and mark the strip where students suggest, without correcting anyone yet.

Direct instruction (12 min): Hand each student a paper strip and fold one along with the class into 4 equal parts. Establish that the whole strip stands for a full barrel, that the four parts must be the same size, and that one of those parts is named 1/4. Shade three parts and record 3/4, saying aloud that 3/4 means three parts of size 1/4. Repeat the fold with a second strip in 6 equal parts and record 1/6 and 4/6 the same way. Stop after each recording to ask what the bottom number counts and what the top number counts.

Guided practice (13 min): In pairs, students fold a third strip into 8 equal parts, then shade amounts the teacher calls out and write the matching fraction on a whiteboard. Circulate and check that partners are holding the strips against each other to confirm the parts are equal. Run a formative check midway: show a strip folded into four parts where one part is clearly larger, and ask for thumbs up or down on whether the small part can be called 1/4. If more than five students vote thumbs up, refold the strip together before moving on.

Independent practice (10 min): Students complete items 1 through 7 of the student handout on their own, using their folded strips as tools. Remind them to write the fraction, not a picture, in the answer space.

Closure and exit ticket (5 min): Students complete handout item 8 alone and hand it in as they line up. If more than five students write 3/5, plan a short reteach with the strips the next morning before any new fraction work begins.

Bellhaven School's Rain Barrel Gauge: A Grade 3 Unit Fraction Lesson — Grade 3 Math
Name: ____________________________ Date: ______________

Student Handout

The rain barrel at Bellhaven School has a paper strip on its side. The strip is folded into equal parts. Each part stands for the same amount of water.

  1. A strip has 4 equal parts. Water fills 1 part. What fraction of the barrel is full?
  2. That same strip has 4 equal parts. Water fills 3 parts. What fraction of the barrel is full?
  3. A second strip has 6 equal parts. Water fills 1 part. What fraction of the barrel is full?
  4. That second strip has 6 equal parts. Water fills 5 parts. What fraction of the barrel is full?
  5. A third strip has 8 equal parts. Water fills 3 parts. What fraction of the barrel is full?
  6. The third strip has 8 equal parts. The barrel is half full. How many parts are filled?
  7. One part of the 4-part strip and one part of the 8-part strip are shaded. The two strips are the same length. Which fraction shows more water?
  8. Ben has a strip with 8 equal parts. He fills 3 parts, so 5 parts are empty. Ben writes 3/5. What fraction of the barrel is really full?

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: 1/4 of the barrel. The whole is cut into 4 equal parts, and 1 of those parts is filled.
  2. Answer: 3/4 of the barrel. Three parts of size 1/4 are filled, and 1/4 and 1/4 and 1/4 together make 3/4.
  3. Answer: 1/6 of the barrel. The whole is cut into 6 equal parts, so one part is named 1/6.
  4. Answer: 5/6 of the barrel. Five parts of size 1/6 are filled, which leaves one empty part.
  5. Answer: 3/8 of the barrel. Three parts of size 1/8 are filled. The bottom number counts all 8 equal parts of the whole strip.
  6. Answer: 4 parts. Half of 8 equal parts is 4 parts, because 4 + 4 = 8. That amount is written 4/8.
  7. Answer: 1/4 of the barrel. Cutting the same strip into 8 parts makes each part smaller than a part of the 4-part strip, so 1/4 is more water than 1/8.
  8. Answer: 3/8 of the barrel. Ben counted the 5 empty parts against the 3 filled parts. The bottom number has to count every equal part of the whole strip, and there are 8 of them.

Differentiation

Support

Provide strips that are already creased so students only fold along existing lines, and give a matching set of loose unit-fraction tiles labeled 1/4, 1/6, and 1/8 that can be laid end to end on the strip. Sit with this group for items 1 and 2 and ask them to say the fraction aloud before writing it. Accept a shaded drawing beside the written fraction as evidence for items 5 through 7.

Extension

Ask students to fold a fourth strip into 12 equal parts, then find every way to show a half-full barrel on their 4-part, 6-part, 8-part, and 12-part strips, recording each as a fraction. Have them write one sentence explaining why the number of filled parts changes while the amount of water does not.

ELL supports

Pre-teach "equal," "parts," "whole," "filled," and "empty" while folding a strip in front of the class, pausing to compare the parts side by side. Post the sentence frame "___ of the ___ equal parts are filled, so the fraction is ___." Allow students to point to the correct strip for item 7 before writing, and pair them with a partner who can restate the item 8 prompt in simpler words.

Extensions

Set the class rain barrel or a tall clear jar under a downspout and have students tape their own folded strip to the side. Ask them to record the fraction shown after each rain over two weeks, then order those fractions from least to greatest and discuss which rain filled the most parts of the strip.