Basic Facts and Strategies Review

Things to know:

Know when a math problem is a basic fact or not (lesson 2.1)

Know what each of the named strategies are, and be able to describe how to use it in finding a basic fact.

• counting on to add (lesson 2.2) (also know the difference between counting on from first and counting on from larger)
• counting back (lesson 2.3)
• counting on to subtract (lesson 2.4)
• using doubles to add (lesson 2.8) (show with equations and ten frames)
• using 10 to add (lesson 2.9) (show with equations, open number lines, Cuisenaire rods and ten frames)
• building up through 10 to subtract (lesson 2.10) (show with ten frames, and open number line, number sentences and Cuisenaire rods)
• backing down through 10 to subtract (lesson 2.11) (show with ten frames, and open number line, number sentences and Cuisenaire rods)
• think addition to subtract (lesson 2.12) (show with equations, bar diagrams and math mountains. Know reasons why it is a good strategy. Know how to describe it in part-whole language (verbally)).

A sample question:

• Explain how to use building up through 10 to subtract to find 14-8

Know what facts each strategy is an efficient choice for.

Sample questions:

• Describe or list all of the facts for which using doubles to add is an efficient strategy
• Write 5 math facts for which using 10 to add is an efficient strategy
• Identify two efficient strategies you could use to solve 12-8, and show how to use them to find the sum
• Explain the difference between counting back to subtract and counting up to subtract. Which strategy is more efficient for subtracting 12-8?

Know how other facts can be derived from memorized facts including partners of 10, doubles and decompositions of numbers less than 10.

Sample questions:

• How can knowing partners that make 10 help you with other addition facts? Explain and give a specific example.
• How does knowing decompositions of numbers less than 10 help you with using the strategy use 10 to add. Explain and give a specific example.
• How can knowing partners that make 10 help you with subtraction facts where the minuend is greater than 10? Explain and give a specific example.
• How can knowing doubles help you with other addition facts? Explain and give a specific example.

Bar diagrams: for a given word problem, draw a bar diagram and a math mountain. Label the bar diagram as well as putting numbers in appropriately. For missing-total problems, write an addition number sentence to find the solution. For missing part problems write subtraction number sentence and missing number addition equation.

Sample questions (make diagrams and write number sentences for):

• Alice gave away 9 pencils to her friends. She had 3 pencils left over. How many pencils did she have to start with?
• Ben has 14 markers. He has 5 more markers than Kyle. How many markers does Kyle have?

Subitizing: Be able to draw diagrams that are appropriate for conceptually subitizing numbers between 5 and 10, and explain how your diagrams make it easy to see the amount without counting.

Teaching:

• Be able to describe reccommended strategies for teaching counting on, counting up to subtract, and making ten to add.
• Be able to explain Rathmell's recommendations for using drill in teaching and learning basic facts.

Answers to practice problems