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These concepts can be confusing to kids.
I believe that Einstein's happiest thought was that if a person jumps off
a cliff (no air), then she has no sensation of weight. This led to his
general theory of relativity.
True weight is mg, while apparent weight is given by a bathroom scale,
which shows the upward support force. Jump off a cliff, and that scale
reads zero. You have no apparent weight, just like those floating
astronauts in the orbiting shuttle. Plenty of true weight. You can also
hang a wood block with a spring scale. Release the block and it falls due
to its true weight. But the scale reads zero while the block falls.
Scale can also be used with fluids. Suspend a 1-kg mass from a spring
scale. It weighs about 10 N. When completely submerged, the scale reads
about 9 N. The difference is the buoyant force. So the buoyant force is
abut 1 N -- the weight of water displaced (which can be measured).
Kids understand these true weight/apparent weight ideas using these scale
activities and their applications.