When first learning to multiply two two-digit numbers your child will use the area model.

To start, your child will use her knowledge of place value to decompose into tens and ones. To decompose means to break apart. Let’s decompose these numbers by the value of each digit.

The value of two tens is twenty. The value of three ones is three. Three tens is thirty. And five ones is five. Decomposing numbers allows your child to use the multiplication fluency she developed in third grade to multiply large numbers with mental math.

So, what is twenty-three times thirty-five?

Three tens times two tens equals sixty tens or six-hundred. Thirty tens times three equals nine tens or ninty. Twenty tens times five equals ten tens or one-hundred. And three times five equals fifteen.

Your child will then add these products together. Six-hundred plus ninety equals six-hundred ninety. One-hundred plus fifteen equal one-hundred fifteen. By fourth grade, your child will fluently add three-digit numbers, like this, using the standard algorithm.

Your child can clearly see why twenty-three times thirty-five equals eight-hundred-five. The area model gives your child a visual representation that decomposes the numbers she is multiplying. At this point in fourth grade, your child is developing a pictorial level of understanding, which will give her a strong foundation for using partial products and, later, using the standard algorithm to multiply.

Before learning any new concept (mathematical or otherwise), it's important to learn and use a common language and label concepts consistently.

To understand equivalent fractions it helps to "see" the fractions by making a drawing to represent them.

This module will give you some practice converting metric distance units.

We're comparing fractions using the info given in this word problem. Can you find the equivalent one?

How many pizzas, pieces per pizza, and eaten pieces were there? It's enough to make you hungry!

What if you wanted to save a fractional amount of your allowance? How would you go about figuring out how much to save? .

Each number in the Fibonacci sequence is the sum of the two numbers before it. Tavia Cathcart Brown shows us how to find those numbers in nature, and what they mean.

In this program students learn about graphing a line based off of transformations of the parent function. Instructor: Cryshel Whitehead (The transcript of this program is available for download at the link below.)

In this video, watch an animated demonstration of using the Pythagorean theorem to find an unknown side of a right triangle. In the accompanying classroom activity, students solve problems in which they apply the Pythagorean theorem to find the sides of right triangles and to determine whether a set of triangle sides form a right triangle. To get the most from this lesson, students should be comfortable using a calculator to find square roots. They should also have experience solving equations involving an unknown square.