I started by telling Sweet Girl I had a magic wand that would help me get the things I wanted. I waved my magic wand and said "Daddy give me that book." Of course he knew not to give it to me. We tried again, and when it didn't work I told Sweet Girl we must be missing the magic words. I whispered the magic words to her and together we said "Daddy, please hand me that book." This time he handed the book to us. From there we talked about how real magic words are words that are nice, make others happy, and help others want to help us. We learned about magic words like thank you, sorry, and saying yes when we ask her to do things.
It was really simple, but Sweet Girl still talks about that lesson. Whenever she uses a magic word, she makes sure to point it out to me just in case I missed it.
Family home evening is one of the best nights of the week. Since my kids are little we are pretty much home together most nights, but it's nice to have a special night set aside to do something together. For some simple and really great ideas for a family night lesson and activity you can also go to lds.org and look at the manual Behold Your Little Ones. It's for the nursery class on Sundays, but the lessons are great for family nights too.