Wednesday, September 25, 2013

Split the Difference: A Marvelous Math Strategy!

This week, Mrs. Ranney's class is working on a
 new type of math word problem.

It is different than other word problems we've done.   
Usually word problems ask questions like:  

How many in all?       How many more?     How many fewer?


Here is an example of the new kind of word problem. 

Photo by Mrs. Ranney

Frogger and Curious George left 45 comments on the blog.
Frogger left 5 more comments than Curious George. 

How many comments did Frogger leave? 
How many comments did Curious George leave?

The answer is:
Frogger: 25 comments
Curious George: 20 comments

In Mrs. Yollis' class, this problem was used:
Panda and Hoppy left 25 comments. 
Hoppy left 5 more comments than Panda. 

How many comments did Panda leave? 

How many comments did Hoppy leave?
 Photo by Mrs. Yollis

Here is a photo of how we solved the problem:

The answer is
Panda: 10 comments
Hoppy: 15 comments

Here is a tutorial created by Mrs. Yollis and one of her former students made
 illustrating our special strategy for solving this type of problem.  


What do you think of this process?

If you want to make up one of these math problems with your parents, please do so! 
 We'll use it for practice in class!


  1. Dear Mrs. Ranney and Class,

    This process is really fun and it makes your brain think hard to solve the problem. I like this process and I love Math.

    I hope you like this question.

    Tristan and Jolie have 213 pieces of candy. Jolie has 13 pieces more than Tristan. How many pieces do they both have?


  2. Dear Mrs. Ranney and class,

    I have a problem for you:
    Jake and Matt have 105 baseball cards. Matt has 15 more baseball cards than Jake.

    How many cards do Jake and Matt each have?

    Do the work on a piece of paper and reply when you figure out the answer.

    Josh (Jacob's brother)

  3. Dear Mrs. Ranney and class,

    I like this strategy because it is easier than the method in math book.
    My mom explained to me with example. I couldn't get the answer with the way in math book quickly.

    Here is the problem to share with class:

    Poppy ate 99 apples and carrots in a week. Poppy ate 7 less carrots than apples.
    How many apples and carrots did Poppy eat each?

    Your friend,

    1. Dear Mrs. Ranney and Class,

      While Michelle was doing her math homework today, I noticed that there was a problem with split difference.
      It's been a while since they learned it at school. I hope that it helped the class to refresh their memory.

      Here I show my work to solve Michelle's problem:

      99 - 7 = 92
      92 can be splitted into 46 and 46.
      Poppy ate 7 less carrots than apples.
      Therefore Poppy ate 46 + 7 = 53 apples and 46 carrots each.
      Check the answer: 46 + 53 = 99
      53 - 46 = 7.

      Do you think my answer is right?


      M★chelle’s M♥m, Josephine

  4. Dear Mr. Ranney and class,

    I have good problem for you:

    My little brother and I have 50 soccer balls. I have 12 more then my brother. How many do each of us have?

    I have another question:
    My sister and I have 15 leotards for gymnastics. My sister has 7 more then me. How many do each of us have?

    and finally:
    My baby brother and I have 23 teeth in all. I have 23 more teeth they my baby brother. how many does my baby brother have?


  5. Dear Mrs.Ranney and class,

    I have a problem for you:
    Noah and Lucas have 1,000 books. Lucas has 508 more books than Noah.

    How many books do they have?


    1. @ Jacob,
      In order to find the anwser for your problem here is what you should do: First, you subtract 508 from 1,000. The answer to that is 492.
      Then, you have to find the half of 492. The answer to that is 246. Then, you add 508 to 246. The
      answer to that is 754. So the final answer to your question is: Lucas has 754 books and Noah has 246 books.


  6. Dear Mrs. Ranney,

    Here are a lot of problems.
    In Mrs. Ranney's class, there are 27 students. There are 5 more girls. How many boys are there? Girls?

    Karen and Makenzie have 28 books in all? Karen has 6 more books than Makenzie. How many books does Makenzie have? Karen?

    Kevin and Loran wrote 34 notes. Loran 2 more notes than Kevin. How many notes did Kevin write? Loran?


  7. Dear class,

    I think the process is great because it helps you figure out the answer quickly and more accurately. It also allows me to double check my work.

    Here is a problem I created for the class:
    My 2 cats, Allie and Daisy, had 125 cat kibbles total for breakfast this morning. Allie had 57 more bites than Daisy. How many bites did Allie have? Daisy?

    Do you think we can figure it out tomorrow in class?




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:) Mrs. Ranney