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What you need
A Two-pan scale, 2 sheet metals of equal size from a magnetic and from a non magnetic soft drink can.
Look for photo 3 for self assembly)
Experiments
Left: The Kindergarten ladies demonstrate to the children that a scale works like a seasaw:
Photo 2: The girl on the right side of the seasaw is more heavy than the boy on the opposite side.
Photo 3: The red pogemon on the self assembled scale is more heavy than the yellow one hanging at the left side.
Right:  The magnetic metal sheet which has disappeared on the right side is more heavy than metal sheet of the same size placed on the right pan.

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