Pupils observe how to spawn male and female pencil sea urchins. They mix together the sperm and ova from the live sea urchin to observe and record the events occurring in the control and experimental groups for fertilization. Thus, investigation to the use of fertilized sea urchin's ova as a bioassay for differing pH levels is explored. Emphasizing critical thinking skills to examine organisms used in research and environmental concerns is enhanced by the participants.