• ## Multidigit Multiplication with Standard Algorithm: The Donut Doze Off

In this Cyberchase video, Bianca has a new job decorating fresh-baked donuts. Her supervisor asked her to decorate 12 trays of donuts, but Bianca thought he meant 12 donuts. When she discovers her mistake, she uses multiplication strategies and an understanding of repeated addition to discover the true scope of her job. In the accompanying classroom activity, students play a game against the teacher in which students get practice multiplying two-digit numbers. This resource is part of the Math at the Core: Middle School Collection.

• ## Area Model for Division

Visualize solutions to multi-digit division problems by modeling them with virtual manipulatives. This interactive exercise focuses on calculating quotients by working with area models and visualizing the distributive property of division. This resource is part of the Math at the Core: Middle School collection.

• ## Determining Surface Area with Unit Blocks

Use your spatial reasoning skills to calculate the surface area when given a 3D figure. This video focuses on a right rectangular prism and shows you how unit blocks can help you visualize, then calculate the surface area. This video was submitted through the Innovation Math Challenge, a contest open to professional and nonprofessional producers. This resource is part of the Math at the Core: Middle School collection.

• ## Solve the Ratio and Proportion Problem Beyond a Shadow of a Doubt

In this video, Harry finds money on the sidewalk. He uses ratio, proportion, and some knowledge about shadows to return it to the rightful owner. In the accompanying classroom activity, students investigate whether there is a consistent relationship between the height of objects and the length of their shadows. This resource is part of the Math at the Core: Middle School Collection.

• ## Code Breaking: Harley Gets a Hint

In this video, Harley moves in with Harry and makes Harry's life miserable. Harley spies on Harry writing in his diary. When Harley "borrows" the diary, he finds it is written in a code using numbers. Harley figures out a pattern with numbers and letters and decodes the page to find it is a message for Harley saying it is time to move out. In the accompanying classroom activity, students create their own codes and clues using whole numbers and fractions. This resource is part of the Math at the Core: Middle School Collection.

• ## Base 60: Babylonian Decimals

Explore a brief history of mathematics in Mesopotamia through the Babylonian Base 60 number system. This video focuses on how a base 60 system does not use fractions or repeating decimals, some of the advantages of a base 60 system, and some components that carried over into the base 10 system we use today, taking math out of the classroom and into the real world.
• ## Who Won?: Comparing Decimals to the Thousandths Place

To figure out who won the race you have to compare their times. This interactive exercise focuses on using what you know about ordering decimals, number lines and rounding to the tenths place and then asks you to think about what numbers could be rounded to get a certain decimal.

• ## Number Line Party: Rounding to Wholes, Tenths, and Hundredths

On some nights only certain numbers can get in to the Number Line Party, what's a decimal to do? This interactive exercise combines activities here appear in two other Number-Line Party lessons and focuses on using what you know about number lines and rounding and then asks you to explain your reasoning and think about what numbers could be rounded to get a certain decimal.

This resource is part of the Math at the Core: Middle School collection.

• ## Number Line Party: Rounding to the Tenths Place

Only numbers with tenths can get in to the number line party, what's a decimal with hundredths to do? This interactive exercise focuses on using what you know about number lines and rounding to the tenths place and then asks you to think about what numbers could be rounded to get a certain decimal.

This resource is part of the Math at the Core: Middle School collection.

• ## Number Line Party: Rounding to Whole Numbers

Only whole numbers can get in to the number line party, what's a decimal to do? This interactive exercise focuses on using what you know about number lines and rounding from the tenths place to make decimals whole numbers and then asks you to explain your reasoning to show comprehension.

This resource is part of the Math at the Core: Middle School collection.

• ## Decimals in Expanded Form

Find the value of digits by exploring the number 342.98. This video focuses on using what you know about place value to determine what each digit represents in a number that extends to the hundredths place.

This resource is part of the Math at the Core: Middle School collection.