Curated OER
Subtracting Fractions with Borrowing
The teacher draws a visual on the white board to show how to change a whole number into a fraction by borrowing. This is necessary because the original written fraction is too small to subtract the second fraction.
Khan Academy
Singapore Math: Grade 3a, Unit 2 (Part 9)
Sal uses numeric expansion to show the process of subtracting four-digit numbers. For example, he expands the number 6004 and writes it as 6000+0+0+4 and 2678 as 2000+600+70+8. When he regroups, viewers can see the actual number exchange...
Curated OER
Subtracting Whole Numbers - Math Help
Subtracting three-digit whole numbers is as easy as following along with this video. You'll discover that you can borrow a ten from the tens column if you need to. Academic vocabulary is used throughout.