Observation method 1: let the magnifying glass close to the object of observation, the observation object does not move, the distance between the human eye and the observation object remains unchanged, and then move the handheld magnifying glass to move back and forth between the object and the human eye until the image is large and clear.
Observation method 2: The magnifying glass is as close to the eye as possible. The magnifying glass does not move, moving the object until the image is large and clear.