Modeling a Subtraction Problem
Trixie was 2 years
and 11 months at the time that this video was made.
The Problem
Trixie is playing with a collection of toy Sesame Street characters.
She has 5 Cookie Monsters and 3 Big Birds. First I ask her, "Are there
more
Cookies or more Big Birds?" When she answers correctly I then ask, "How
many more?" (This may be Trixie's first
exposure to this type of problem - what I call "Hard Subtraction 1.")
What To Look For In This Video
- Trixie has no problem with the question, "Are there more Cookies or more Big Birds?"
- On the other hand, Trixie seems to think that to find "how many more" she should count all the Cookie Monsters, not just the extra ones. (This is a pretty typical misunderstanding.)