The main purpose of this study is to examine 1) differences in the views on example sentences between learners and teachers in English grammar instruction and 2) the appropriate number of words in an example sentence. There are various opinions on preferable qualities of example sentences, but there is little research focusing on the opinions of both learners and teachers. Therefore, two investigations are conducted on learner and teacher participants: 97 English teachers and 271 students at upper secondary school in Japan. The first investigation consists of a questionnaire for English language teachers, asking how many words should be used in example sentences to make grammar instruction more useful, or how important they think example sentences are in grammar instruction. The second investigation is made up of another questionnaire for learners, asking how important they think example sentences are in reviewing particular grammatical items as well as in learning them. The second questionnaire also asks the learner participants to write down English sentences useful in English learning or those which they remember well. The result implies that learners tend to think less of example sentences in learning English grammar, and 2) that, in contrast, teachers tend to think more highly of example sentences in teaching English grammar. This study also presents the number of words in an example sentence for effective grammar learning, based on data from learners, teachers, English textbooks, and English grammar materials.