Fractions « Math Mistakes:

I’ve been reading some constructivist stuff lately, so…

What resources does this student have for refining their understanding of fractions?

(Thanks for the submission, Dionn!)

What’s the fastest way to help this 9th grade student?

How did the student make the decision to plot 1/4? Tell a story.

Source: Chris Robinson

This is a snapshot of a book by Robert Ashlock, Error Patterns in Computation.

Penny for your thoughts in the comments. How does a book like that relate to a blog like this?

Also, jump in if you have anything interesting to say about this sort of fractions error.

See the title of the post.

What is the significance of this mistake? Say something smart about this piece of student work in the comments.

Above are three different answers to 4 divided by 1/4. What understanding stands behind each of those wrong answers? How do you teach division by fractions?

I arbitrarily designate some mistakes to be “classics,” and this here is one of them.

No need to identify the mistake. It’s right there. But let’s get some wisdom in the comments. What is the significance of this mistake? Does knowing that this mistake is common change the way that you do (or should) teach?

[I didn't exactly know how to tag this post, but it's from a 9th grade classroom. For CCSS I tagged 5th grade.]