How did this kid come to believe in this algorithm?

Thanks to Amy Burk for the submission.

  • We taught the student that multiplication is repeated addition, so that’s what they did, repeated addition.

    The part where they made some attempt to multiply the numbers and then scratched it out, that slays me.

  • Like Joan said above, the student is doing repeated addition. Adds 3 three times; adds 9 nine times. As a next step I might ask the student to multiply 1 x #, and show how adding 1 will get # + 1 rather than #.

  • mpershan

    Tamara Pearson says: “Students are so often told that multiplication is the same as repeated addition. This student is just misunderstanding the meaning of repeated addition.”