This short video and interactive assessment activity is designed to teach second graders an overview of addition (sums to 1,000).

This short video and interactive assessment activity is designed to teach third graders an overview of addition (sums to 1,000).

The purpose of this task is to address the concept of opportunity cost through a real world context involving money.

The goal of this task is to help students understand the commutative property of addition by examining the addition facts for single digit numbers. This is important as it gives students a chance, at a young age, to do more than memorize these arithmetic facts which they will use throughout their education.

This short video and interactive assessment activity is designed to teach third graders an overview of before and after (time).

This short video and interactive assessment activity is designed to teach second graders an overview of before and after (time).

This short video and interactive assessment activity is designed to teach fourth graders about telling the time - before and after.

The purpose of this task is to help students understand composing and decomposing ones, tens, and hundreds. This task is meant to be used in an instructional setting and would only be appropriate to use if students actually have base-ten blocks on hand.

This short video and interactive assessment activity is designed to give fourth graders an overview of time conversion between words and numbers.

This short video and interactive assessment activity is designed to teach second graders an overview of time patterns.

This short video and interactive assessment activity is designed to teach third graders an overview of time patterns.

This short video and interactive assessment activity is designed to give fourth graders an overview of telling time to quarter and hour.

This TV 411 segment features a lesson from Question Man on how to informally calculate 15% tips at restaurants.

This series of word problems requires students to determine which problems can be solved by multiplying 1/8_2/5.

This task presents an incomplete problem and asks students to choose numbers to subtract (subtrahends) so that the resulting problem requires different types of regrouping. This way students have to recognize the pattern and not just follow a memorized algorithm--in other words, they have to think about what happens in the subtraction process when we regroup. This task is appropriate to use after students have learned the standard US algorithm.

This instructional task requires students to add four numbers to find the solution.

This short video and interactive assessment activity is designed to teach fourth graders about number riddles (numbers up to 100,000).

This short video and interactive assessment activity is designed to teach fifth graders about turning numbers into words within word problems.