J. MARTIN, NORTHLAND COLLEGE

Math,

Furry, Fluffy, and Glowing

Scientists have discovered that some mammals give off a glow!

By Mara Grunbaum

From the October/November 2022 Issue

Learning Objective: Students will compare and order decimals related the fluorescence of a type of flying squirrel.

Lexile: 870L; 670L

Focus Area: Fractions and Decimals,

One night in May 2017, Jonathan Martin carried a special ultraviolet (UV) flashlight into his backyard. He heard a flying squirrel squeak. The animals appear brown and white in regular light. Under Martin’s UV light, the squirrel’s belly glowed neon pink!

Martin is a forestry scientist in Ashland, Wisconsin. He knew that many animals—including some birds, fish, frogs, insects, and lizards—can fluoresce (flu-RESS). This means they soak up invisible UV light and release visible light in bright, glowing colors. But this ability had almost never been seen in mammals, like flying squirrels.

Rick & Nora Bowers/Alamy Stock Photo

This is how it appears under visible light.

To confirm this finding, Martin and his colleagues traveled to museums to study their collections. The team photographed preserved flying squirrels at the Science Museum of Minnesota under UV light. They all glowed hot pink.

At the Field Museum in Chicago, the team discovered even more fluorescent mammals. A springhare from Africa and a platypus from Australia glowed under UV light too.

All the fluorescent mammals the team found have something in common: They’re most active at night. The ability to glow could help mammals communicate. Scientists need to watch the animals in the wild to learn more.

Comparing and Ordering Decimals

Watch a math helper video about how to compare decimals using number lines and place value charts.

Math Talk

Why is place value important when working with

decimals

Comparing Decimals

What to Do

A place value chart shows the value of a digit based on its position. It can help you compare decimals.

Example

Which number is greater: 1.8 or 1.6?

Table showing the ones and tenths columns separated by column of decimals and the tenths circled

• First, write the numbers in a place value chart. Don’t forget the decimal point!

• Next, compare the digits from left to right. Both numbers have the same value in the ones place, so we move to the tenths place. 8 tenths is greater than 6 tenths.

So 1.8 is greater than 1.6.

Now You Try It

The table shows fluorescence scores for a type of flying squirrel. These scores are how scientists measure an animal’s natural fluorescence. A higher score means a brighter glow. Use the table to answer the questions below.

Table showing the different body parts of a flying squirrel and the corresponding flourescence score

Source: Journal of Mammalogy

BODY PART	FLUORESCENCE SCORE
Abdomen	14.8
Chin and neck	2.5
Back	2.3
Tail	11.9

A. Write the fluorescence scores for the squirrel’s abdomen and tail in the place value chart below.

B. Which score is higher?

Table showing the ones and tenths columns separated by column of decimals

Does the squirrel’s tail fluoresce more or less than its chin and neck?

Which part of the squirrel fluoresces more—its chin and neck or its back?

Order the squirrel’s fluorescence scores from least to greatest.

Multimedia

video (1)

Comparing and Ordering Decimals

Watch a math helper video about how to compare decimals using number lines and place value charts.

Read Story

Comparing and Ordering Decimals

Watch a math helper video about how to compare decimals using number lines and place value charts.

1. SPARK ENGAGEMENT.

Before or after reading the article, spark a discussion based on the following questions.

What are some adaptations animals have that help them survive in the wild?

What types of numbers would scientists who study animal adaptations be interested in?

If you were a nocturnal animal (an animal that is active at night), what kind of adaptation would be useful to have?

2. INTRODUCE THE MATH CONCEPT AND VOCABULARY.

Display the following numbers, stacked directly on top of each other: 2,468; 24.68; 246.8. How are these numbers similar and different? (Possible answers: They have the same 4 digits; two are decimals; they have different values.)

These numbers have the same digits, but the place value of each digit is different in each number.

Place the numbers in a place value chart. What do you notice about this chart?(Answers will vary.)

Is the tenths place greater or less than the tens place? (less) Which of these numbers has the greatest value? (2,468) Why? (because it is the only number with a digit in the thousands place)

Today we will use place value charts to compare and order decimals.

Play the math video, "Comparing and Ordering Decimals."

3. WORK THROUGH THE "WHAT TO DO" BOX.

How does a place value chart help you compare decimals? (Answers will vary.)

Why did we compare the digits in the tenths place instead of just the digits in the ones place? (The digits were the same in the ones place, so we needed to move to the next place value to the right.)

If 7 was added to the hundreths place of 1.6, making it 1.67, would 1.8 still be the greater decimal? Explain. (Yes, 1.8 would still be the greater decimal. Eight tenths is still greater than six tenths, so 1.8 is greater than 1.67.)

4. REINFORCE WITH MATH PRACTICE.

Have students complete questions 1 through 4 on page 9.

Community Building

Jonathan Martin worked with a team to find other fluorescent mammals. Working as a team can allow you to do something bigger than one person can do alone! Have each student trace their hand, cut it out, and then write one character trait that a good teammate has. Arrange all your class's hands together to make a large wreath for your classroom wall.