The 100th Day of School and Number Sense

Celebrating the 100th day of school offers older elementary students the opportunity to dig into the physical meaning of large numbers and the quantities they represent. You can also explore the theme in art projects and in social studies and science lessons as well as making the wonderful literature connections suggested below.

The 100th day of school is a day to let your imagination go wild! Here are a few ideas you might use to get your class started:
• Have students make a stack of 10 pennies and then predict how tall a stack of 100 pennies would be. Then have them build the stack to see how close their prediction was to the real thing. Students can measure the stack in inches and centimeters.
• Ask students to determine how many \$100 bills are needed to have \$1 million.
• Have students come up with three different arithmetic problems that have 100 as the answer.
• Students can work in groups to find the answer to these questions: What time will it be in 100 seconds? In 100 hours? What day will it be in 100 days? What month will it be in 100 months? What year will it be in 100 years? What year was it 100 years ago?
• Ask students to find out how to say "100" or the word "hello" in as many different languages as they can. (See suggestion #75 in 100 Ways to Celebrate 100 Days by Bruce Goldstone.)
• Have students collect 100 cans of food to deliver to a food pantry.
A good way to conclude the day is to ask students to figure out when the next 100th day of school will occur and mark it on the calendar.

In the lists of resources below, you'll find hundreds of other suggestions for using everyday objects and readily available books to deepen students' understanding of numbers when estimating, calculating, and making sense of the world.

From the ORC Collection

## Lessons and Activities

Concentration (ORC# 13606, grades K–6) features six interactive, online activities that involve matching equivalent graphic representations to numbers, geometric shapes, multiplication facts, or fractions and percents. One or two students can play this matching game at their own pace to either practice facts or reinforce their understanding of mathematical representations.

The following two lessons are designed to support development of number sense. In the first lesson, Count on Math: Every Breath You Take (ORC #4373, grades 3–5), students estimate the number of times they breathe in one hour, and the class graphs the estimates, finds the mean and median estimates, and discusses outliers. Students consider how they might estimate the number of times they breathe in one day and how they might determine the actual number of breaths per day. The second lesson, Count on Math: Making Your First Million (ORC #4374, grades 4–7), involves finding the size of 1 million by figuring out how long a million days is, how long it would take to count to 1 million on a calculator, how long it would take to write the numbers from 1 to 1,000,000, and other such questions.

In An Apple a Day (ORC #224, grade 4), students make estimates to analyze the number of apples per acre and visualize the magnitude of 1 million.

The ninth caller in a radio contest in the Million Dollar Giveaway (ORC #250, grades 3–7) can walk away with a suitcase of money—as much as \$1 million in cash in dollar bills. Students need to devise plans to estimate the amount of money it will take to fill a given suitcase.

In the first of two activities that focus on number patterns, Displaying Number Patterns (ORC #1439, grades 2–4), students work with virtual hundred boards and calculators to highlight and display patterns and relationships among numbers when skip counting. In the second activity, Patterns to 100 and Beyond, students skip-count both forward and backward starting at various numbers. Students can move beyond 100 and below zero using just the calculator.

The MegaPenny Project (ORC #11225, grades 5–10) website offers a step-by-step tour of what large numbers look like when illustrated with U.S. pennies. The goal of the site is to help people conceptualize what very large numbers such as 1 million, 1 billion, and 1 quintillion really mean. Each number page has a table at the bottom, listing the value of the pennies, size of the pile, weight, and area (if laid flat).

## Student Bookshelf

 100 Ways to Celebrate 100 Days by Bruce Goldstone features 100 great ideas to keep a focus on 100 for the first 100 days of school. The cleverness of the presentation reflects the approach to number sense the author celebrated in Great Estimations and Greater Estimations! These last two books will appeal to readers and estimators of all ages. Counting Our Way to the 100th Day! by Betsy Franco contains 100 charming, illustrated poems that engage students in thinking about numbers in fascinating and unusual ways. This book will delight readers of all ages. The clever rhymes and colorful illustrations in 100 Days of School by Trudy Harris will intrigue students as they think about addition combinations for 100 objects.

## Resources for Students

See Number & Operations (Grades 3–5) from the National Library for Virtual Manipulatives for a great collection of online learning tools for building students' ability to understand and use numbers.

The online learning tool Can You Say Really Big Numbers? presents a fun way for students to practice saying and reading any large number that they type into the tool.

This printable Interactive 100 Number Chart (1–100) can be used online and offline to develop students' ability to skip-count and to find factors and multiples.

Have students explore the 100th-day date at the History Channel's This Day in History. While they're at it, they can also check what happened on their birthday!

With the Powers of Ten, students can visualize the relationship between very big and very small numbers expressed as powers of 10.

## Background Resources for Teachers

The ORC Mathematics Bookshelf features information about using outstanding trade books in the classroom. One bookshelf entry, One Hundred Hungry Ants (ORC #11140, grades 3–5), offers an entertaining introduction to the factor pairs of 100. Students will find factor pairs for numbers along with other interesting information about primes and the number of factors for a number.

Two books by David M. Schwartz on the ORC Bookshelf focus on numbers and number sense. How Much Is a Million (ORC #11106, grades 3–8) and On Beyond a Million (ORC #11110, grades 6–10) feature engaging introductions to powers of 10, exponential notation, huge numbers, nonsense "numbers" (like gazillion), and infinity.

Also on the bookshelf are The King's Chessboard and One Grain of Rice, both of which tell the same classic tale of the astounding effect of doubling a single grain of rice each day over a period of 30 days.

On Joan Holub's 100th Day of School Website: 300 Celebration Ideas for Educators, learn about the possible origins of celebrating the 100th day of school and see 89 creative ideas for celebrating the day while reinforcing basic mathematics skills such as estimating, counting, measuring, and sequencing.