Does putting "similar to" make a simile?

In my English literature cl, we had to write a paragraph with one sentence making a simile. I put that something is similar to something else. I'd give you the sentence I wrote, but my teacher has the ignment at the moment. However, he let us look at it, and it showed I had points taken off because he didn't believe my sentence made a simile. His reasoning was that a simile has "like" or "and." The Oxford dictionary says it is a comparison of one thing to another. Since "similar" is a synonym of "like," the meaning of the statement isn't changed. Am I wrong in thinking I deserved those points?