Once I make a whole from three-fifths, I end up with one and two-fifths. That’s some deep understanding of fractions! I can decompose four-fifths into two-fifths and two-fifths.
What you see above sounds more like, I know I need two more fifths to add to three-fifths to make a whole. There is no additional cost to you, and I only link to books and products that I personally use and recommend. This post contains affiliate links, which simply means that when you use my link and purchase a product, I receive a small commission. Recognizing that seven-fifths is greater than a whole, they would proceed to apply a procedure for converting an improper fraction to a mixed number. They’d add the two fractions to get a sum of seven-fifths (Hopefully! How many would say seven-tenths?). Think about how we would normally teach students to solve that problem.
Take a look at this fraction addition problem. Not too long ago I wrote about the power of part/whole thinking, and how an understanding that begins in Kindergarten has tons of applications throughout the elementary curriculum.
