Common Core Standards
Grade 4
Writing W.4.3.D
Use concrete words and phrases and sensory details to convey experiences and events precisely.
This standard is looking for imagery. We hope they're painting pictures when they read, and we hope they're painting pictures when they write their own words. You shouldn't be pulling teeth for this one: fourth graders are creative, and imagery can make writing activities fun. So have them put their painting caps on and get to it. Bob Ross is optional.