1.NBT.2 Place Value Uncategorized

Mistake Hall of Fame: Cena

Cena, wherever she is these days, deserves a medal. This video is a classic.

Here we get to see how the teacher followed up with the student, so let’s tackle these questions:

  1. What can we say that Cena does know?
  2. What is going through her head as she answers these questions? Where does she go wrong?
  3. What are the teacher’s moves in this clip? What is her strategy for uncovering the student’s errors?
3.OA.1 Multiplication

Multiplication Issues (from Khan Academy)

This student has done a great job articulating their issue. How would you help?

5.NBT.3 Decimals

From Khan Academy: Comparing Decimals

No, Sal Khan did not actually submit this question. But Andyhav3 asks:

What’s this student getting at with “the right side of the decimal,” and how might you help Andyhav3?


[Click here to see how your approach compares to how his question was actually handled.]

Fractions Numbers & Operations -- Fractions

“Fractions are really small things.”

Today isn’t a sample of student work, exactly. It’s an interview with a kid.




[Source: How Students Learn: Mathematics in the Classroom, p.314]

3.NF.2 Fractions

How big is three-eighths?

In the student’s work below, what is “it” and why does the student think that matters?


[Source: ]