Working in Level E; Lesson 22
Worksheet 20 (problem - bottom line; 2nd problem)
My dd and I are having trouble subtracting 89 and 3/8 from 1 and 7/8.

I am trying to think how to pose my question...first of all, I can work the problem the way I was taught to subtract fractions but I know it's not the RightStart way and I want to be consistaet. But, I am so limited in my math ability that I can't see how to show her on the fraction chart. Also, I know this problem wouldn't come up if you hadn't already addressed the way to handle it in prior lessons but I can't find how to solve it the RightStart way.

Please take me step by step - very detailed. You will not offend me if you do! Often my dd understands before I do - especially when it comes to fractions.

Thank you for your help and concern! I am becoming more math literate b/c of RightStart and though I never think I'll be able to "speak the language" I understand things that I never have until teaching my dd's. My trouble with math started in early elementary and I just barely got by and graduated high school with very little understanding. I am thrilled that it won't be this way for my kids - thansks to you!

Leslie Snyder

Dear Leslie,

Thank you for your post.

89 3/8 - 1 7/8

First subtract 89 - 1 = 88

Now you're left with 88 3/8 - 7/8

3/8 -7/8 When you subtract this you're left with -4/8 because you subtract the difference between 3 and 7 which is -4.

Having -4/8 means you need to subtract 4/8 from 88. How do you do this? You can get out your fraction chart and look at subtracting 4/8ths from 1. You may already have noticed that 4/8th is equal to 1/2, therefore you're subtracting 1/2 from 88 which is 87 1/2.

Does this make sense? If not please let me know so I can work on doing a better job of explaining this. I will email you directly with my phone number so you can give me a call directly if you would like a verbal explanation, otherwise you can call our customer service line and one of our customer service people can also assist you as well.

Please try not to "tell" you child how to find the answer. Have you child discover the answer. Provide the fraction chart as a manipulative and as a visual. Then give your child time to think it through by asking questions.

Please feel free to email, post or call with any other questions you might have.

Sincerely, Rosine

Rosine,

Thanks so much for this step by step answer to the problem. I have read it over and it makes perfect sense. Once I work it through with my dd if we have any further questions I'll let you know.

The only remaining question/comment that I have is should I have known based on the previous lessons and levels to allow her to use a negative number to find the solution? I wasn't thinking that was an option because we hadn't really gotten to negative numbers yet; we've dealt with them little but not to the point that I realized it was okay to allow my dd to use them in solving problems. Maybe I need to think outside the box a little more regarding this!

Thanks again,
Leslie

Dear Leslie,

I'm glad that my explination made sense to you. Leslie, it's not really about using negative numbers. I just mentioned a negative number because there was no other way to state it when writing it out. What I was hoping to express was that as you are comparing the fractions you would see that you needed to move into a whole again to continue to subtract the fraction.

I think you are right on when you say "Maybe I need to think outside the box a little more...." Also, I would encourage you to give your child the questions and let your child wrestle with them. You do not need to give the answer or the how to to do it right away. Give your child the space to think through it even if that space means putting it aside for an hour or two or even for the day. By doing this as parents we allow our children to have that "think" time they need to discover how math works. This is also how new inventions are created.

Let me know if you have other questions or comments.

Sincerely, Rosine
PS While working through RS children seem to understand and use negative numbers without even being formally introduced, however, again in this situation I was only using a negative number as a visual.