Final answer:
Safety signs and symbols are crucial for maintaining safety in science labs, and they can be found both on lab walls and on lab sheet directions.
Step-by-step explanation:
The statement safety signs and symbols can be posted on the walls in science labs or can appear on student lab sheet directions is True. Safety signs and symbols play a critical role in maintaining a safe environment in the laboratory by communicating important information quickly and clearly. They can indeed be posted on walls in science labs, as well as be included on the lab sheets provided to students. These signs provide guidance on how to handle different chemicals, indicate where safety equipment like fire extinguishers and eyewash stations are located, and offer important reminders, like never eating or drinking in the lab, to promote proper safety protocol.