The equations __ + 4 = 10 and 3 + __ = 8 illustrate which mathematical concept to introduce?

• A. data interpretation
• B. fact families
• C. repeating patterns
• D. place value

Answer: (B)

Fact families involve related addition and subtraction facts that use the same numbers. These two equations show how numbers come together to form a sum and how those same numbers relate within that group. In the first blank setup, 6 and 4 combine to make 10. In the second, 3 and 5 combine to make 8. A fact family uses the three numbers to generate related facts like 6 + 4 = 10 and 10 − 6 = 4 (and 10 − 4 = 6), and similarly for 3, 5, and 8. Presenting these relationships helps students see how the parts connect to the whole, reinforcing how addition and subtraction mirror each other within a small set of numbers. Data interpretation would require charts or graphs, repeating patterns involve sequences that recur, and place value deals with the value of digits by position, none of which capture the connected addends and totals shown here.