This open-ended interactive Flash applet helps students develop operation and number sense, facility with number facts, and understanding of equations. Users designate single-digit whole numbers or integers and operations on both sides of an equation and test for balance. Users can enter numbers by using the keyboard or arrow buttons or by dragging number tiles. Each element can be hidden and a seesaw may be toggled on/off. Teachers may use this applet to lead instruction, or students may use it independently to perform specific investigations or explore freely. Supplementary documents include Objectives, containing teaching suggestions, and a student recording sheet.

This web page links to a series of 6 pages of number puzzles (141 altogether) which develop flexibility and computational fluency. Puzzles provide a target number and several other numbers, each of which must be used exactly once to arrive at the target. Solvers may use any of the four basic operations (addition, subtraction, multiplication, division) and parentheses. Most puzzles are solvable with whole numbers, but a few solutions involve fractions. Each puzzle contains a hint as well as at least one solution. Red asterisks indicate more difficult puzzles.