Common Core Standards
Grade 2
Writing W.2.2
Write informative/explanatory texts in which they introduce a topic, use facts and definitions to develop points, and provide a concluding statement or section.
Second graders could go on and on about their opinions, but this standard gives you a good excuse to introduce some history, science, or technical texts to the classroom, too. This standard's pretty close to the first grade version, but second graders are expected to add a little more detail to their informative writing. Besides just naming a topic, they should be able to introduce it. Along with supplying facts about said topic, they should be able to use relevant facts to develop ideas about the topic. As always, a little concluding statement—or section, if we're feelin' fancy—never hurt nobody.