Check out Study Jams! a free educational resource from Scholastic. is a collection of free educational videos covering over 200 math and science topics. The lessons are short and are geared toward children in grades.
Scholastic StudyJams video on Weathering and Erosion. They also have videos for Landforms and Soil. The videos are awesome and use superheroes to explain the concepts. (Need to look at for Age range that it is appropriate.