References
- Mason , Jack L. and Troxel , Vern . 1979 . “University Students as Leaders for Field Trips.” . Science and Children , 16 ( no. 7 ) April
- Askham , Leonard R. 1973 . “Audio-Tutorial Instruction for Environmental Education.” . Journal of Environmental Education , 4 : 4 – 5 .
- United States Forest Service . Investigating Your Environment (A collection of activities developed by teachers and resource people and distributed by the U.S. Forest Service.)
- Virginia Department of Education . June 1981 . Earth Science Field Guide , June , Richmond , Va. : Division of Science and Elementary Administration, Commonwealth of Virginia . (Region I)
- Virginia Department of Education . June 1978 . Supplementary Activities for Enriching the Teaching of Earth Science , June , Richmond , Va. : Commonwealth of Virginia .
- Heller , Robert L. 1962 . Geology and Earth Sciences Sourcebook , N.Y. : Holt, Rinehart and Winston, Inc. . American Geological Institute
- National Science Foundation . 1972 . Crusty Problems: Probing the Natural World , Englewood Cliffs , N.J. : Silver Burdett . Intermediate Science Curriculum Study