Looking for a low-tech, open-ended challenge for today? This can be printed off, or use a sheet of lined paper or graph paper to make an 11 x 13 grid. Yup, 11 squares in one direction, and 13 in another.
Ask a simple question. What is the smallest number of squares that will fill the grid completely? If you do nothing, the 11 x 13 grid will take 11×11 (121) + 2×11 (22) = 143 squares.
The entire lesson plan can be found on the Youcubed site.