Using iMovie to Edit
I have edited with a lot of different software, and I do believe iMovie is one of the easiest to learn for newbies; I highly recommend beginning with iMovie or Windows Movie Maker if you're a beginner. Here is an example of a video created with iMovie.
Trailers are also excellent ways for children and even adults to begin learning the basic principles of using iMovie for editing purposes. Below you will see an example of a video created to advertise for our annual wax museum. Trailers are very easy to make and have a professional look to them. I am also including the introduction to our weekly announcements, to see a different type of trailer.
Adobe Premiere
My preferred editing software to use in my classroom is Adobe Premiere, specifically with my older children. This software has a higher level of difficulty, but there are endless possibilities with this tool as far as graphics, green-screen technology, titles, transitions, and more. I feel as though if students can eventually learn how to edit with this tool, they can learn how to edit with most available to them throughout life. Below is an example of a video created using Premiere for editing.