National Council of Teachers of Mathematics
The Math Forum: The Cylinder Problem: Middle School Lesson
This lesson offers an interesting, hands-on experience for middle school students studying cylinders. Students will create cylinders, and measure and compare their volumes.
Maths Challenge
Maths challenge.net: Perimeter Sequence
A "one star" geometry problem that requires finding the visual pattern and applying logic with basic math skills to find the perimeter from the sequence.