The relationship between children's performance in solving open sentences and the factors of sentence type, number size, and context was investigated. The study also identified and classified the methods of solution used. Thirty-two third graders were individually given an orally administered test on open sentences. Four types of open sentences were used: N + a = b, a + N = b, a - N = b, and N - a = b, where N was the placeholder. Half of the test items included a verbal problem presented with the open sentence, while the remainder of the items gave only an open sentence. Multivariate analysis of variance was used. Results showed that open sentences of the type N - a = b were significantly more difficult than those with smaller constants. Children used an average of five different solution methods on the items. (Author/DT)