Question

fix the one plural or possessive error.
most childrens interest in stars wanes as they get older. but one childs fascination led him to study physics at harvard and astrophysics at columbia university. that child, neil degrasse tyson, became director of the world-renowned hayden planetarium in 1996.

Explanation:

The error is the incorrect plural possessive "childs'". The singular noun "child" has an irregular plural "children", but here we need the singular possessive form to show one child's fascination. The singular possessive of "child" is "child's".

Answer:

Most children's interest in stars wanes as they get older. But one child's fascination led him to study physics at Harvard and astrophysics at Columbia University. That child, Neil deGrasse Tyson, became director of the world-renowned Hayden Planetarium in 1996.