Smithsonian Institution
Smithsonian Learning Lab: Prehistoric Climate Change and Why It Matters Today
Introduce students to environmental issues by studying a time of rapid global warming that occurred 50 million years ago. Lessons, video segments and interactive activities will engage students as they learn about average annual...
National Council of Teachers of Mathematics
The Math Forum: Finding 2.5 Percent of a Number
This site provides shortcuts and hints on how to do more complicated percentages without a calculator. For others beside 2.5, scroll down the left column and click percentage of choice under "Percents."