Nonstandard Measurement Playground

Before rulers and centimeters were invented, people measured things using everyday objects like hands, feet, sticks, or stones. These are called nonstandard units because everyone has a different-sized hand or stick.

• A paper clip is about 3 cm long
• An eraser is about 5 cm long
• A building block is about 4 cm long
• Different units give different numbers for the same object

To measure an object, line up copies of your unit from one end to the other without gaps or overlaps. Count how many fit. That number is the measurement.

• Place the first unit at the very start of the object
• Add units one after another with no spaces
• Count each unit to get the total length
• Include partial units by rounding to the nearest whole

You can only compare two lengths fairly if you use the same unit for both. A pencil that is 8 paper clips long is not necessarily longer than a leaf that is 10 paper clips long unless you know both measurements used the same paper clip.

• Same unit makes fair comparisons possible
• Different units make numbers misleading
• The Challenge mode lets you practice this skill

The key idea in measurement is that the count and the unit always go together. A bigger unit fits fewer times, so it gives a smaller number. A smaller unit fits more times, so it gives a bigger number.

• Bigger unit gives a smaller number
• Smaller unit gives a bigger number
• The actual length of the object does not change
• Standard units like cm and inches were created so everyone gets the same answer