Summarizing is one of those skills that may seem very easy to a teacher but can be difficult for students who have not been properly taught how to summarize. For many years I did not even teach my seventh and eighth grade students how to summarize. I would just ask them to summarize texts and then get mad at them when they failed to produce quality summaries. I was wrong in doing this. Now I always teach my students how to write summaries.
Additionally, as per the Common Core State Standards, summaries should not contain opinions, background knowledge, or personal information; rather, a summary should be entirely text based. After years of learning to make connections between the text and themselves, students must be retrained to keep themselves out of their writing in regards to summaries. Teaching this skill surely warrants some of your class time.
Here are some resources that I used in my classroom to teach my students how to summarize. I hope that you find this page useful: