Hey guys I have a question. So I am teaching a demo lesson on fractions for fifth grade, how to add unlike denominators to be specific. People have recommended I use fraction bars to teach the conceptual understanding based on common core's focus on teaching concept before traditional rules. The trouble is I'm starting to think this can only go so far. For example when I am teaching a problem like 3/7 + 2/4, is there really a way to teach using fraction bars? You eventually have to introduce the LCM method. So is fraction bars just a basis to start the subject? So far for my lesson I am introducing the conceptual reason why we have to find unlike denominator using a fraction bar example, but then I am teaching the LCM method. Is this ok?

Using fraction bars is a perfect way to introduce the concept of adding (and eventually subtracting) fractions with unlike denominators. Students have a visual/concrete proof that 1/2 + 1/3 does not equal 2/5. It will eventually lead to the algorithm using the least common multiple. Go with it, and let us know how

You could use pictures or set models as well for fractions with denominators like 7. There are other ways outside of fraction bars and circles. These manipulatives are used to start the understanding and then push the students farther.

Fraction bars are a good way, but I would never say there is any 1 best method to teach fractions. I find with 5th graders that giving them several different methods to solve a problem is helpful. Fraction bars helps most of my students, but I find I have to use other methods for some other students.

The fraction bars are just a visual manipulative, and they do a great job building conceptual understanding. Having said that, you draw pictures of groups to teach conceptual understanding of multiplication and division, but it wouldn't replace the eventual algorithms that are necessary to working out multiple digit problems.

The whole point of using fraction bars is so that students can set up a visual representation of the problem. The "LCM method" CAN be introduced using fraction bars; the catch is you have to have enough pieces available for students to manipulate and truly represent the problem. It helps to start with a simpler problem; I would actually start with unit fractions. For example, 1/2 + 1/4. Students can line up each piece end-to-end and glue them down on a paper. Then, challenge them to write the sum. Hopefully they will see that since the pieces are different sizes, you can't truly add them together. Most students will figure out that you can "replace" the 1/2 with two 1/4 pieces. Underneath the original problem they can glue the new pieces down and write "1/4 + 1/4 + 1/4 = 3/4". The problem when you get to more complex problems, like 3/7 + 2/4, is that you need to have a bunch little 1/28ths cut out. Not the best! If you really want to focus on the conceptual reason for finding a new denominator with fraction bars, stick with simple problems like: 1/8 + 1/2 1/3 + 3/4 3/4 + 5/6 Then challenge students to find a smaller piece that can "replace" each of the fractions. Have them figure out WHY the "LCM method" works. In my opinion, the conceptual part needs to be at least one whole lesson. I feel like showing examples of pictures and then just teach them "find the LCM!" isn't really all that better than just teaching them rules in the first place. If they really are going to make meaning of the "why and how" of common denominators, they need some hands-on experience with it.

I think the question needs to be, which algorithms are truly necessary? Sorry if this is a hijack! One algorithm that works for one students might not work for another. Not every student needs to be an expert at the traditional model of long division if they can find other methods to divide. For example, I have a student who DOES use grouping. Just last week he showed 336/3 by drawing 3 people and then underneath each person writing 100 + 10 + 2 = 112