Abstract: The teaching device or aid hereof includes a simulated, flexible bowel which is attached to a manikin having an interposed, masking position between learning and teaching participants using the aid, so that the teaching participant can selectively flex the simulated bowel, out of the view of the learning participant, preparatory to and during the attempt by said learning participant to properly pass the sigmoidoscope within said simulated bowel, as would be required during an examination of a living person.The inventive device hereof is only illustratively described in connection with a sigmoidoscope, it being understood that it can also be used in teaching proper handling techniques with other medical instruments, e.g. a bronchoscope, a peritoneoscope, etc.