Almost all of what people learn from outdoor educational settings such as zoos and gardens stems from the exhibits themselves or signs about the exhibits. Evaluation of the various forms of visual communication in outdoor educational settings is necessary to determine the effectiveness of exhibitions, educational activities, and/or conservation programs. A preliminary study was conducted at the Phoenix Zoo, in the Arizona Trail--Reptile Section, to determine visitor use and satisfaction. Study techniques included pre- and post-viewing surveys, interviews, and observation of visitors. The most frequently described fact that visitors remembered was the information contained on a sign developed by a school group explaining the difference between "venomous" and "poisonous." In contrast to other signs in the exhibit, this sign contained a clear, simple message beginning with a thought-provoking question. Many visitors do not read the small signs accompanying exhibits, possibly because of their placement height and small print. Guidelines suggested to help designers improve the effectiveness of visual communication in this type of setting include: (1) arouse learner curiosity with a simple, thought-provoking question or title: (2) supply a succinct answer below the question; (3) use simple, clear language; (4) use large, clear text; (5) keep text to a minimum; (6) utilize pictures and graphics to help learners see to what the text is referring. (Author/SWC)