Need experiment for Robotic Arm in Science Fair

Hello all-this may be a little "elementary" but i need help-My 11 year old son is doing a science fair project on "What Tasks are Better Suited for Robots than Humans" it has to use the scientific method of course....- We ordered the Robotic Arm Edge for around $50 and would like to use it to show a task better suited for a robot-we would like to show participants trying to accomplish the same task without the aid of a robot.-that would be the manipulated or independent variable....at first we thought we can put a cottonball stuck at the base of pins coming out of a block of styrofoam to show how this task would be dangerous for a human as opposed to a robot-(Maybe simulating robots that are used in operations to do precision tasks) but we dont want to invite people to stick their hands with pins trying to retrieve a cottonball....then we thought of using the game "operation: and invite participants to first use their hand to retrieve one of the harder objects and then try the robotic arm and see who made the red nose light up more, hopefully proving that the robotic hand is more precise than the human hand.....any ideas of what we can do? Thank in advance.........