Number Sentences and the Rules of Operations

On this Quest, you'll discover…

Write, solve and check number sentences, and use the properties of operations.

• Write a number sentence that describes a problem situation, using a placeholder for the unknown.
• Solve and complete number sentences by inspection, and by trial and improvement.
• Check a solution by substituting it back into the original number sentence.
• Use the commutative, associative and distributive properties of operations with whole numbers to make calculations easier — you can use them before you have to name them.
• Explain the additive property of 0 and why adding 0 leaves a number unchanged.