This link leads to part of Math Forum's "Ask Dr. Math" feature within their website. It contains a list of interesting questions about place value, sent in by students, which have been answered by Dr. Math.

• Base Block applets
These models are placed on a place-value chart. If ten of one type are dragged to the column to the left, they snap together. If a piece is dragged one column to the right, the pieces break apart.

• Comparison Estimator
Two sets of small objects are shown and the task is to decide which set has more. The actual counts are then given. The same applet also allows for comparisons of length and areas. Try to get close, really close, or almost perfect.

• Estimator
One set of small objects are shown and the task is to decide how many there are. The actual counts are then given. The same applet also allows for estimations of length and areas. Try to get close, really close, or almost perfect.

• Hundreds Board and Calculator
A calculator is used to create skip-counting patterns on a hundreds chart. You can start the pattern on any number and skip by any number. The chart extends to 1000. A second pattern will show with red dots on top of the first pattern.

• Key concepts in place value
This site acts as an entire independent lesson on place value. It begins with a "First Glance" tutorial, then moves to a more "In-Depth" explanation of key concepts in place value, and concludes with an interactive "Practice" session for students.

• Lots of Dots and A Million Dots on One Page
These explorations of big numbers are only a hint at the array of ideas found on this website. A lot is beyond the elementary school, but anyone interested in big numbers and measures will certainly be intrigued. See a dot for every second of the day!

• Place-value issues
This site addresses many of the place-value issues in the Kindergarten through 8th grade curriculum. Options for students include tutorials, along with interactive explorations where they can complete online activities to practice skills relating to place value.

• Printable activities relating to place value
For elementary teachers, this link provides several printable activities relating to place value. The activities would be appropriate for second through fifth graders.

• The 100th Day of School
The book, The 100th Day of School, is a popular one to help young students begin to understand place value. This site was posted by the illustrator of the book, Joan Holub, and contains hundreds of ideas and links for celebrating the 100th day of school in the primary grades.

• The Mega Penny Project
A fascinating look at large numbers in terms of stacks of pennies. Stacks from 1 penny to a trillion pennies are shown with visual referents, value, weight, height if stacked, and more. Great for large-number concepts.

• The Place Value Game (Jefferson Lab)
The goal is to make the largest possible number from the digits the computer gives you. Digits are presented one at a time. The player must place the digit in the number without knowing what the next digits will be. It's fun and also good for understanding ordering of numbers.