The Woodie Guthrie Archive has a lesson plan to teach children and bloggers about the Dust Bowl
What mistakes do people make today with regard to the land? Unsound agricultural practices continue. So do unsound logging practices, strip mining, overgrazing, the use of agrochemicals and pesticides, high water consumption, destruction of rain forests, over consumption of non-renewable resources. Students can branch out into issues of ecology and stewardship of the earth. Look into local ecology groups who can link your class with special hands-on projects.
But looking a pictures give one a better, deeper and scarier appreciation of what we need to avoid repeating. There are reasons to be scared.