One question to ask. "Is the oldest story we have the same as being there?" A good answer says: no. The bath story was first written down about two hundred years after Archimedes died.

One thing to do at the table. Hang a spoon from kitchen scales by a thread and read them. Then lower the spoon, still hanging, into a bowl of water and read them again. The water pushes up. That part Archimedes wrote down himself.

Make a two-column page. Pick a family story that is older than anyone at the table. Who first told it to you? Who told them? Write the chain in ink. Write the best bit in pencil.

The grown-up layer. Lan's wrong tool is a common one for older children: treating the earliest surviving source as an eyewitness. The crown-and-bath story comes from Vitruvius, writing about two centuries after Archimedes; it is not in Archimedes' own works, although the floating principle is (On Floating Bodies). In 1586 the young Galileo argued that the spilled water would be too small to measure and that a hydrostatic balance was probably the real method. "Nobody knows" is an honest answer, and it is not the same as "false".