A concept that is really simple, yet made difficult by the way we teach it is Liquid Measurement. We usually teach it by requiring students to memorize a chart similar to this:
2 cups = 1 pint
2 pints = 1 quart
2 quarts = 1 gallon
What's wrong with that? We learned it that way didn't we? It worked for us, why shouldn't our students or children learn it the same way? Because there is a much easier way.
Buy milk in different size cartons. Once milk (or juice) is consumed, wash and save carton. When introducing the concept of liquid measurement, show and identify the different size cartons to students. Allow students to fill the smallest carton with water. Pour the water into the next size carton. Repeat until the larger carton is filled. Allow the students to complete the following chart:
? cups = 1 pint
? cups = 1 quart
? cups = 1 gallon
? pints = 1 quart
? pints = 1 gallon
? quarts = 1 gallon
Allowing students to discover the amount rather than memorize a chart is much more meaningful to them. Other useful objects are measuring cups which are sold in sets. Again using these objects to complete the chart.