There are a plethora of resources to use to address this topic for LDS families. See other resources here. It's an index for LDS families that includes links to over a dozen Friend articles on the subject of pornography.
A Family Home Evening PlanSong
"The Lord Gave Me a Temple," (Children's Songbook)
For a fabulous flipbook, head over to OCD Primary Chorister and print pages 1-16 for the first verse (half of the pages are text only. You may wish to print double-sided).
This five-minute video comes from overcomingpornography.org. Many children will be exposed to pornography for the first time before they are 12 years old. It's hard to put together a feel-good video to address a sickening possibility, but that's what this is.
If you're having difficulty viewing the embedded video, view it instead on overcomingpornography.org.
After the video, ask if any of the children want to talk to you about anything they've seen.
Move from computer, to tv, to a book. Pretend a bad picture just came up. Ask your children what they need to do.
Call it what it is. Close it, turn it off, or look away. Tell a parent/trusted adult.
Vanilla Cupcakes with Chocolate Frosting
If you want to get really fancy, add a cream filling.