Simplify the following text for a Grade 11 native English-speaking person.
Original: In The Canon of Medicine in 1025 AD , he laid down rules for the experimental use and testing of drugs and wrote a precise guide for practical experimentation in the process of discovering and proving the effectiveness of medical drugs and substances .
Simplified: Clinical trials were first introduced in Avicenna 's The Canon of Medicine in 1025 AD , where he laid down rules for the experimental use and testing of drugs . He wrote a precise guide for practical experimentation in the process of discovering and proving the effectiveness of medical drugs and substances .