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I'm trying to come up with some math problems (word or otherwise) that get to the meaning of adding zero, but I'm getting stuck because it seems just too simple to me.

I have come up with questions like "John is having a birthday party and he invites five friends over but nobody shows up. How many people are at the party?". While this question gets to the problem at hand, it might be too simple to understand the meaning of adding zero. This problem also suffers from the possibility that first graders will answer like so, "Well there would be three people at the party because John's mom and dad would be there too."

Any ideas?

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2 Answers 2

up vote 4 down vote accepted

I suggest you modify your birthday party idea to include different types of people, such as friends from school, friends from soccer, etc. Then in general you need to add together the number of attendees from the various categories, and sometimes that will entail adding zero.

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Assuming this is a two-student group.

Give student 1 three pieces. Give student 2 two pieces. Tell student 1 to take all of their pieces in the pot. Ask the students how much are in the pot. Now ask student 2 to put all their pieces in the pot. Ask the students how much are in the pot. Now ask student 1 to take all their pieces and put them in the pot. Now ask the students how much is in the pot.

In the last addition to the pot, student 1 didn't have any more pieces, therefore student 1 added zero and the count did not increase.

This solution can scale to larger groups of students and the students addition order could be rearranged to show that adding zero at the beginning or the end will not change the outcome.

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