Elementary School Operations & Algebraic Thinking Subtraction

Lilikoi, which is a word that I totally didn’t have to look up, and Subtraction

From the submitter:

Students were presented with the photo of the bowl of lilikoi and the story: Brayden and Caelyn picked lilikoi.  There were 13 lilikoi in the bowl. Caelyn picked 5 lilikoi.  How many lilikoi did Brayden pick? The second photo shows student predictions.  If a student changed their mind, we crossed out their previous prediction and wrote the new one.

Give a theory as to why students answered 13 before answering 5 (or 8).

Thanks to Mitzi Hasegawa for the excellent submission.

2 replies on “Lilikoi, which is a word that I totally didn’t have to look up, and Subtraction”

The story doesn’t say that both pickers put their lilikoi in the bowl. There are clearly not 5 in the bowl, so the alternative is that the bowl has Brayden’s picking in it, which means he picked 13. Caelyn probably is holding hers in a different bowl, or her hand,or a pocket.
I can’t help you with the 5 🙂

Not sure if you’re serious, but I’d agree that the story is probably too vague. Really, we don’t have a solid idea of the relationship between the goal (the number that Brayden picked) and any of the other numbers. If you force an answer from students in that context, I wouldn’t be surprised by anything they offered.

I’m also skeptical that there are exactly 13 lilikoi in the picture, I’m getting 14-16 depending on how many are partially hidden under the top layer. Depending on how the problem was stated, I could see that being a potential confounding factor.

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