Adding and Subtracting fractions with a Common Denominator: Multi-step problems


 Students often struggle with multi-step problems for a lot of reasons. In my experience, the most common one is they stop too soon. For example, in the first lesson below, the student may add up the fractions of the rice gathered by each of the two sisters and stop there. However, the question asks, “How much of the rice is LEFT to gather?”

(For that confusion, we have our Start at the End video, but you can go check that out later.)

A second obstacle is just not knowing how to solve one or more parts of the problem. A student may not understand how to convert a whole number to fraction, for example.

Speaking of examples, I think the more examples students have in the more different contexts, the better. Here are two examples of multi-step word problems with adding and subtracting fractions. We provided these in PowerPoint and PDF because not all schools have a PPT license and sometimes, even if you do, the slides don’t show exactly right on a different computer even though they looked perfect on your computer at home!

DOWNLOAD THE PDF or PPT HERE:

 PDF POWERPOINT
 Adding and subtracting fractions  Adding and subtracting fractions
 Subtracting fractions  Subtracting fractions

Prerequisite information to adding and subtracting fractions with a common denominator

Sometimes, the problem is that a student lacks the prerequisite information. What’s a denominator? How do you add fractions with the same denominator? If you think that’s the case, show the video below first, then move on to the presentation.

https://youtu.be/Z3jcQ39E0as

Learn adding and subtracting fractions with a common denominator in the Fish Lake adventure game!

Fish Lake logo - two Ojibwe men in a canoe

End your class with style learning fractions by playing Fish Lake

Description: In the Fish Lake adventure game, players practice with fractions while learning math problem-solving strategies. The storyline is set in the context of Ojibwe history and culture. Spear fish, hunt deer, pack for a long journey, all of the time learning how to apply fractions in real situations, whether it’s dividing up the work or sharing a pot of stew.


Recommended for Grades 4-6
Math Standards alignment Grades 4-6
Math topics Fractions
Culture Ojibwe
Available for iPads, Mac or Windows computers

NOTE: If you get a message about ‘unidentified developer’ on a Mac, here is how to fix it in 5 seconds or less.

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