The accuracy and simplicity of this experiment are amazing. A wonderful project for students, which would necessarily involve team work with a different school and most likely a school in a different state or region of the country, would be to try to repeat Eratosthenes' experiment.

This short video and interactive assessment activity is designed to teach fourth graders about estimating measure by image: centimeters or meters?.

This short video and interactive assessment activity is designed to teach fifth graders about estimating the measure of objects by image: feet or inches?.

Students learn that buoyancy is responsible for making boats, hot air balloons and weather balloons float. They calculate whether or not a boat or balloon will float, and calculate the volume needed to make a balloon or boat of a certain mass float. Conduct the first day of the associated activity before conducting this lesson.

Franklin works with Laverne to create a budget for a job painting a room, in this video segment from TV 411.

This short video and interactive assessment activity is designed to teach fourth graders about estimating measure by description - multiple choice.

Harry estimates how long it will take him to get to the front of a long ticket line in this Cyberchase video segment.

The task is designed to show that random samples produce distributions of sample means that center at the population mean, and that the variation in the sample means will decrease noticeably as the sample size increases. Random sampling (like mixing names in a hat and drawing out a sample) is not a new idea to most students, although the terminology is likely to be new.

This short video and interactive assessment activity is designed to teach fifth graders about estimating the measure of items by description: inches, feet, or yards?.

The purpose of this task is for students to show they understand the connection between fraction and decimal notation by writing the same numbers both ways.

The purpose of this task is to provide students with an opportunity to explain fraction equivalence through visual models in a particular example.

In this task students prove that linear functions grow by equal differences over equal intervals, and that exponential functions grow by equal factors over equal intervals.

This problem illustrates how an exponentially increasing quantity eventually surpasses a linearly increasing quantity.

In this task students observe using graphs and tables that a quantity increasing exponentially eventually exceeds a quantity increasing linearly, quadratically, or (more generally) as a polynomial function.

This problem shows that an exponential function takes larger values than a cubic polynomial function provided the input is sufficiently large.

The purpose of this task is to help students see the "why" behind properties of logs that are familiar but often just memorized (and quickly forgotten or misremembered). The task focuses on the verbal definition of the log, helping students to concentrate on understanding that a logarithm is an exponent, as opposed to completing a more computational approach.

This task and its companion, F-BF Exponentials and Logarithms I, is designed to help students gain facility with properties of exponential and logarithm functions resulting from the fact that they are inverses.

This short video and interactive assessment activity is designed to teach second graders an overview - hundredths.

This short video and interactive assessment activity is designed to teach second graders an overview - tenths.

This short video and interactive assessment activity is designed to teach third graders an overview - hundredths.