Three Types of Math Problems to Use in Kidblog


Recently I have been using Kidblog to facilitate online math discussions with my students.  I posted several questions, asked the students to answer them in the comments, and told them I would wait awhile before approving any comments.  This gave students a chance to think about the problems before they read anyone else’s answers.

In an offline math discussion I pose a question and give students some time to think about their answer either on paper or with a partner or both.  Then students report their answers whole group and describe how they got the answer.  Students consider how others solved the problem and agree, disagree, or ask questions.

By adapting this process to a blog post with comments, more students could be involved at once at each stage of the discussion.  I found three problem types that worked well for this exercise: stretch your thinking problems, find the mistake problems, and odd one out.

“Stretch Your Thinking” Problem

While playing a video game, Lisa scored 400 points.  Ali scored three times the number of points Lisa scored.  Ezra scored 200 more points than Lisa.

Write an equation with at least one variable to show the answers to the following questions, and then solve.

  1. How many points did each child score?
  2. How many more points did Ali score than Ezra?

I went through the problems that appeared on the homework, changed the names, numbers, and situations, and created story problems that aligned with the algebra unit I was teaching.  I wanted students to write and solve an equation, because that is our current learning target.  I approved only the comments that followed those directions.

“Find the Mistake” Problem

Sarah is planning a party for her classmates. The punch she wants to make has a ratio of 3:2 orange juice to apple juice.

At the store, she finds quarts of orange juice and gallons of apple juice.  She buys three containers of orange juice and a gallon of apple juice.

She believes she will have enough juice for 28 cups of punch.

What is her mistake?  What should she buy instead?

I learned that this problem is the type we need more practice answering.  They didn’t understand the problem.  They didn’t know how to convert.  They didn’t take time to convert.  A few students answered the questions correctly, and I plan to use their correct examples when I reteach this type of problem.  I haven’t used a blog post as an exit ticket for a lesson, but I plan to.  Analyzing their answers gave me quick information about what to teach next.

Odd One Out

Decide which set doesn’t belong and give reasons for your answers.

  • 100 pennies
  • 8 quarters
  • 8 nickels
  • 25 dimes

Most students chose “8 nickels” because it is the only one that was less than a dollar.  A few students chose other sets and gave their reasons.  I deliberately chose four sets that could have more than one correct answer.  I have seen this activity work with sets that had a more definite answer.

Once I have approved the comments, students go back and reply to other student comments.  Just like in an offline discussion, students can agree, disagree, and question.  We have already worked on how to disagree respectfully, and because everyone knows each other in real life they tend to be kinder to one another than what typically happens in online forums.

About the Author
Mary J. Bauer is a fifth grade teacher in Mountlake Terrace, Washington. She has been teaching elementary students for twenty-five years. She also blogs at

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