This work tested the learning in environmental science education activities involving middle school and undergraduate students. It was verified whether participation just once improved previous knowledge; if biodiversity understanding on the trail is more effective using manual guidance than using instructors' supervision, and if three consecutive activities increase understanding. Activities were conducted with three schools on the Brazilian savannah and consisted of oriented walk on the interpretive trail, aquatic insect sampling and identification under microscope. Daily activities increased student´s knowledge, especially on second and third days of activities, when the subjects addressed were completely new for students. The oral guidance from the instructors was more efficient than the use of manual by children possibly because teaching/learning process is usually almost entirely supplied by teacher. The greatest gain was verified at the third day of activity reinforcing that consecutive activities can effectively improve the retention of understanding.