“Thomas Petra has taught math at every level for more than 20 years and encountered dubious students at every grade level. That’s why he developed Real World Math, a free website with lessons based on Google Earth aimed at grades 5 – 10. “I was trying to show them actual applications of the math ideas that they see in the textbook,” Petra said.” via Looking For Real-World Math Problems? Try Google Earth! | MindShift.