Difference between measurement and weight

Dear teachers,

My little sister asked me what a gram is.
What came to my mind was
“A gram is a measurement unit of weight”.

But I thought that weight was a subset of measurement,
so I gave her a shorter answer instead:
“A gram is a measurement unit”.

I am not sure which is the best.
Please help.

Thank you.
Kitty

In my opinion

“Gramme” is a measurement unit of mass.
“Newton” is a measurement unit of either weight or force. (Kilopond, “kp” as well, 1kp=9.81N)

A gram or gramme is a measurement unit of mass. Mosrt non-scientific people consider it to be a unit of weight and this is a common expression.