This is an instructional task related to deepening place-value concepts. The important piece of knowledge upon which students need to draw is that 10 tens is 1 hundred.

This short video and interactive assessment activity is designed to teach third graders about counting vertices and sides in various shapes.

The objective of this lesson is to gain automaticity counting to 100 and to establish the importance of multiples of ten. The final goal of this lesson is for students to be able to count by tens and articulate the term for this.

This short video and interactive assessment activity is designed to teach fourth graders about counting the angles in a closed figure.

This short video and interactive assessment activity is designed to teach fifth graders about counting the number of perpendicular lines.

This task involves solving equations with rational coefficients, and requires students to use the distributive law ("combine like terms"). The equation also provides opportunities for students to observe structure in the equation to find a quicker solution, as in the second solution presented.

This task presents a real world application of finite geometric series. The context can lead into several interesting follow-up questions and projects. Many drugs only become effective after the amount in the body builds up to a certain level. This can be modeled very well with geometric series.

In this video segment from Cyberchase, the CyberSquad must get into a vault before Hacker, Buzz and Delete by cracking a code of shapes and numbers.

This short video and interactive assessment activity is designed to teach fourth graders about creating largest and smallest numbers given digits.

This short video and interactive assessment activity is designed to give fifth graders an overview of comparing decimals.

Students practice crossing from one family to the next in counting forward with this concentration game.

This word problem requires students to create expressions to calculate gas milage for a vehicle.

In this Cyberchase video segment, Shari Spotter gets help from the CyberSquad in doubling a recipe for crumpets.

One common mistake students make when dividing fractions using visuals is the confusion between remainder and the fractional part of a mixed number answer.

With your mouse, drag data points and their error bars, and watch the best-fit polynomial curve update instantly. You choose the type of fit: linear, quadratic, cubic, or quartic. The reduced chi-square statistic shows you when the fit is good. Or you can try to find the best fit by manually adjusting fit parameters.

This short video and interactive assessment activity is designed to teach third graders an overview of capacity (english units).

The purpose of this task is to introduce or reinforce the concept of a function, especially in a context where the function is not given by an explicit algebraic representation. Further, the last part of the task emphasizes the significance of one variable being a function of another variable in an immediately relevant real-life context.