More or less than 1 gallon?

A standard milk jug or large juice container holds 1 gallon — students can use this familiar reference to estimate whether other containers hold more or less.

A gallon is large enough to be meaningfully different from smaller containers, helping students develop a strong sense of volume relative to a concrete, familiar standard.

Building intuition about what a gallon looks like prepares students for the formal study of customary capacity units (cups, pints, quarts, gallons) in 3rd grade.