The White Dot

A kindergarten class had a homework assignment to find out something
exciting and relate it to the class the next day.

When the time came to present what they'd found, the first little boy
the teacher called on walked up to the front of the class, and with a
piece of chalk, made a small white dot on the blackboard and sat back
down.

Puzzled, the teacher asked him what it was. 'It's a period,' he replied.
'I can see that,' said the teacher, 'but what is so exciting about a
period?

'Darned if I know,' he said, 'but this morning my sister was missing
one, my mom fainted, my dad had a heart attack, and the boy next door
joined the Navy.'