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Classroom activity Grade 3 Math

Skipjack Pond Dip Net Cards: A Grade 3 Line Plot Activity

A 40-minute grade 3 activity where groups measure twelve paper creature cards from a fictional pond survey to the nearest half inch and build a floor line plot.

Objectives

  1. Students will measure lengths to the nearest half inch using a ruler.
  2. Students will place measured data on a line plot marked in whole and half inches.
  3. Students will answer how-many and how-many-more questions from a completed line plot.

Vocabulary

Key words: line plot, half inch, dip net, survey, data

Teacher overview

People who check on the health of a pond often sweep a dip net through the shallow water, sort what they catch into a tray, and measure each creature before returning it. Skipjack Pond in this activity is fictional, and the twelve paper cards students measure stand in for a catch that was invented for the lesson. Groups of four measure their card set to the nearest half inch, then walk each card to a floor line plot made from masking tape and place it above the matching mark. The activity teaches the concept directly, because the stack of cards standing above each tape mark is the line plot itself, and students read their answers off a graph they built with their own measurements. The cards are cut to exact half-inch lengths, so every group's line plot comes out the same and the class can compare results.

Activity Directions

Step 1, setup before class (6 min). Prepare one set of twelve cards per group, letter them on the back to match the handout table, and cut them to these lengths: cards A and B are 1 inch, cards C, D, and E are 1 and one-half inches, cards F, G, H, and J are 2 inches, cards K and L are 2 and one-half inches, and card M is 3 inches. Do not write the lengths on the cards, since the group measures them. Lay one strip of masking tape per group across an open stretch of floor. Mark each strip at 1 inch, 1 and one-half inches, 2 inches, 2 and one-half inches, and 3 inches, spacing the marks evenly and labeling each one.

Step 2, explain how the activity works (4 min). Show the class a ruler and point out the halfway mark between two inch numbers. Hold up one card, measure it aloud, and walk it to the matching mark on the floor tape. Explain that each card placed above a mark is one piece of data, so the taller a stack grows, the more creatures were caught at that length.

Step 3, measure (12 min). Groups of four measure all twelve cards, taking turns so each student measures three cards. The group writes each card's length on the handout table as it is measured. Students who disagree about a length remeasure together before recording.

Step 4, build the floor line plot (8 min). Each group carries its cards to its own tape strip and places each card above the matching mark, lining the cards up in a neat column. Once every group has placed its cards, the class walks along the strips and compares the finished plots.

Step 5, record and answer (6 min). Students return to their seats and answer handout items 1 through 6 using their group's floor plot and their own table.

Step 6, debrief (4 min). The activity ends when every group has placed its cards and answered the six items. Ask two closing questions aloud: which mark has the tallest column of cards, and what a tall column tells us about the pond survey. Take one answer for each before collecting the handouts.

Skipjack Pond Dip Net Cards: A Grade 3 Line Plot Activity — Grade 3 Math
Name: ____________________________ Date: ______________

Student Handout

A dip net survey at Skipjack Pond caught twelve creatures. Each card stands for one creature. Measure each card to the nearest half inch and write its length in the table.

Card Length
A
B
C
D
E
F
G
H
J
K
L
M
  1. How many cards measured 2 inches?
  2. How many cards measured 1 and one-half inches?
  3. Which length has the most cards above it on the line plot?
  4. How many cards are shorter than 2 inches?
  5. How many cards are on the line plot in all?
  6. How many more cards measured 2 inches than measured 3 inches?

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: 4 cards.
    Cards F, G, H, and J each measure 2 inches, so the column above the 2-inch mark holds 4 cards.
  2. Answer: 3 cards.
    Cards C, D, and E each measure 1 and one-half inches.
  3. Answer: 2 inches.
    The 2-inch mark holds 4 cards, which is more than any other mark on the plot.
  4. Answer: 5 cards.
    Two cards measure 1 inch and three cards measure 1 and one-half inches, so 2 + 3 = 5 cards are shorter than 2 inches.
  5. Answer: 12 cards.
    Adding every column gives 2 + 3 + 4 + 2 + 1 = 12 cards, which matches the twelve cards in the set.
  6. Answer: 3 cards.
    Four cards measure 2 inches and one card measures 3 inches, so 4 − 1 = 3 more cards.

Differentiation

Support

Give these students a ruler with the half-inch marks highlighted in one color and the inch marks in another, and let them line each card against a pre-marked strip instead of reading the ruler cold. Assign a partner to check each measurement before it is recorded. Allow students to count the cards in each floor column by touching them rather than reading the numbers off their table.

Extension

Ask students to predict what the line plot would look like if the survey caught six more creatures, all of them 2 and one-half inches long, and to redraw the plot with those cards added. Have them explain why a line plot shows the shape of the catch more clearly than a written list of twelve lengths does.

ELL supports

Pre-teach "dip net," "survey," "length," and "line plot" using a photograph of a net and a tray beside a simple drawn plot with three marks. Model the measuring sentence aloud, "This card is ___ inches long," and post it where every group can see it. Let students place their cards on the floor plot before answering any written item, so the graph is the reference rather than the words.