A girl studies fuzzy caterpillars on green garden leaves

The Caterpillar Data Mystery

Sara found fuzzy caterpillars in her garden. Some are long, some are tiny. Can a line plot help her compare their lengths?

4th Grade Math

Step 1: Read the X Marks

0

X1/4

XX2/4

XXX3/4

X1

Sara made a line plot. Each fraction shows a length in inches. Each X stands for one caterpillar. How many caterpillars are 3/4 inch long?

Three X marks sit above 3/4. Each X means one caterpillar, so 3 caterpillars are 3/4 inch long.

Step 2: Find the Tallest Stack

0

X1/4

XX2/4

XXX3/4

X1

To interpret a line plot, compare the stacks of X marks. Which length has the most caterpillars?

The tallest stack has 3 X marks, and it sits above 3/4. More caterpillars are 3/4 inch long than any other length.

Let's Remember

How to Read a Line Plot

          Step 1: The number line shows measurements as fractions.

          Step 2: Each X above a number means one measurement.

          Step 3: To analyze the data, compare the stacks and use the fraction values.

A line plot is like a city skyline. The tallest tower shows the most common measurement!

Step 3: Find the Difference

0

X1/4

XX2/4

XXX3/4

X1

The longest caterpillar is 1 inch. The shortest is 1/4 inch. One inch equals the equivalent fraction 4/4. What is 4/4 − 1/4?

4/4 − 1/4 = 3/4. Subtract the numerators: 4 − 1 = 3. The denominator stays 4.

Watch Out!

A Sneaky Mistake

          Do NOT subtract the number of X marks!

          The longest measurement has 1 X and the shortest measurement has 1 X.

          1 − 1 = 0 is wrong. Subtract the lengths: 4/4 − 1/4 = 3/4 inch.

One more trap: never add the denominators. 1/4 + 1/4 = 2/4, not 2/8!

Read the Plot!

X2/8

XX3/8

XXX4/8

X5/8

XX6/8

Ana made this line plot of her ribbon lengths in inches. How many ribbons did she measure in all?

Count every X mark: 1 + 2 + 3 + 1 + 2 = 9 ribbons. The tick marks show lengths, not the total.

Word Problem

X3/8

XX4/8

X5/8

6/8

X7/8

Leo's line plot shows his beetle lengths. His two longest beetles measure 5/8 inch and 7/8 inch. If they line up end to end, how long are they together?

5/8 + 7/8 = 12/8. Keep the denominator! 12/8 = 8/8 + 4/8, which is 1 4/8 inches.

What Goes in the Blank?

XX2/8

3/8

X4/8

XXX5/8

6/8

X7/8

Rosa's line plot shows leaf lengths in inches. Subtract the numerators to find the difference between the longest and shortest leaf.

7/8 − 2/8 = ?

7/8 − 2/8 = 5/8. Subtract the numerators: 7 − 2 = 5. The denominator stays 8.

Longer Than 2/4?

XX1/4

XXXX2/4

XX3/4

X1

Omar measured seashells for his collection. How many shells are longer than 2/4 inch?

Look to the right of 2/4. Two shells are 3/4 inch and one shell is 1 inch. 2 + 1 = 3 shells.

Make the Plot!

Mia's String Lengths (inches)
1/8,  3/8,  3/8,  5/8,  3/8

1/8

2/8

3/8

4/8

5/8

Mia is building her line plot. How many X marks should she draw above 3/8?

The length 3/8 appears three times in the list. Draw one X for each measurement: 3 X marks.

Challenge! Two Steps

X1/8

X2/8

3/8

XX4/8

5/8

6/8

X7/8

Jade's plot shows worm lengths. Lay the two shortest worms end to end. How much shorter are they than the longest worm?

Step 1: 1/8 + 2/8 = 3/8. Step 2: 7/8 − 3/8 = 4/8. The pair is 4/8 inch shorter.

What could you measure at home to make your own line plot? How would fractions of an inch make your data more exact?

Great Work!

0/9

correct

interpret analyze fraction numerator denominator equivalent fraction