Grow mold, germinate seeds, observe objects with a magnifying glass, or trap a bug. Hundred of uses with these deep set plastic petri dishes! The Petri dish 4-pack is a great addition to the Science Accessory portion of your Science Center. Each pack includes 4 empty petri dishes, 100mm x 25mm. Scientific Skills: Experimenting, Observing, Predicting, Drawing Conclusion, Exploring, Investigating and Communicating.