Liquids,
salts, or anything that can be poured into containers can be measured
using various containers. The volume of a container that is filled with
a liquid or solid is often called its capacity.
Various tools can be used to measure
capacity. Eyedroppers, cups, liter bottles, graduated
cylinders, and beakers are just a few types of containers that can be
used to measure capacity.
Capacity
is the amount a container can
hold. It is usually measured in units such as gallons, quarts, pints,
cups, fluid ounces, liters, and milliliters.
Customary
8 fl oz = 1 cup
2 cups = 1 pint
2 pints = 1 quart
2 quarts = 1/2 gallon
4 quarts = 1 gallon

Metric
The milliliter
(mL) is a metric unit used to measure the capacities of small
containers.
The liter
(L) is equal to 1,000 mL, so it is used to measure the capacities
of larger containers. 
Now, let's decide which units should be
used to measure the capacity of each item.
 baby aspirin  milliliter
 glass of milk  cup
 bottle of water  quart
 orange juice  half gallon
 large soda  liter
 gasoline  gallon

Let's
practice
