(This is another lesson from Here a Little, There a Little,. It was designed to spend a week memorizing the Psalm and reinforcing it through 5 activities.)
Thanksgiving
Help your child memorize Psalm 100 by finding pictures to illustrate the verses.
Psalm 100 – A Psalm of Thanksgiving
Make a joyful shout to the Lord, all you lands! 
Serve the Lord with gladness; 
Come before His presence with singing.
Know that the Lord, He is God; It is He who has made us, and not we ourselves;
We are His people and the sheep of His pasture.
Enter into His gates with thanksgiving,
And into His courts with praise.
Be thankful to Him, and bless His name.
For the Lord is good; His mercy is everlasting,
And His truth endures to all generations. 
Prayer: Thank you for all you have given us and all you do for us. Help us to always have a grateful attitude toward You and others.
Activities for younger preschooler:
Laugh and sing a lot
Sing and smile while changing his diaper or dressing him and talk about being happy to serve him.
Show a picture of sheep – let him feel wool. Talk about being God’s lamb that He takes care of.
Take a day and give thanks for every little thing: toothbrush, clean sheets, water, soap, diapers, etc.
Start a thank you box of pictures of things to be thankful for. Show them as you say, “Thank you God for ______”
Activities for older preschoolers:
Laugh and sing a lot
Talk about the fact that serving God is really serving others. Do an act of service with a cheerful spirit. (rake leaves, bake and share cookies, or simply tie his shoe and talk about how you are happy to serve him.)
Find a picture of a sheep, mount it on cardboard, then cut it into a puzzle. Talk about how we belong to God and He cares for us as the shepherd cares for his sheep.
Take a day and give thanks for every little thing: toothbrush, clean sheets, water, soap, crayons, etc.
Make a thank you box by filling a box with pictures of things and people to be thankful for. Each night let him pull out a few and lead him to tell God thank you.
Songs:
see and hear these at http://www.trainupthechild.org/2010/11/09/keeping-thanks-in-thanksgiving-songs/
We Are Thankful (tune of Are You Sleeping)
We’re Glad Today
We’ve Got So Much