Is glass heavier or lighter when it's hot than when it's room temperature?

Trying to do some science homework. The whole question goes as follows “If the (glass) crucible containing the silver chloride is not cool when its mass is determined, will the calculated percent of silver be too high or too low? why?”

I’m thinking that if the glass is heavier, the percent of silver would be less because there would be a greater difference from when I first massed the crucible at room temperature.