Solving a Subtraction Word Problem Using Place Value

Khan Academy

This educational video guides students through solving a math word problem involving subtraction with double-digit numbers. The narrator presents a scenario about a teacher named Mrs. Henry who starts the year with 64 crayons and ends with 31, challenging viewers to calculate how many crayons were used. The video demonstrates two distinct methods for solving the problem: constructing a subtraction equation using algebraic thinking and utilizing visual place value blocks to physically see the difference. Key themes include subtraction strategies, place value understanding (tens and ones), and the relationship between addition and subtraction equations (fact families). The video explicitly breaks down numbers into their constituent parts—for example, showing 64 as six groups of ten and four ones—helping students visualize abstract numbers as concrete quantities. For educators, this video serves as an excellent model for connecting abstract arithmetic to visual representations. It is particularly useful for introducing students to the concept of "finding the missing part" in a subtraction problem (Total - Part = Part) and for reinforcing column subtraction without regrouping. The dual approach allows teachers to differentiate instruction for students who prefer visual methods versus those ready for standard algorithms.