Using your old Christmas cards or some of your Royalty free Christmas clipart graphic images, select the pictures you want to use. Just print out and cut your selected Christmas graphic images. You will need three Christmas card regular sized images to make the Christmas placemat.
Once you've found a usable image, print yourself a copy of any images with labeled parts. Then use a paint program to white out the labels and print that copy for your child. Your child can label or color the image and have both art and science lesson at the same time.
Something to remember is to never use artwork unless you know it is in the public domain. Many popular images such as cartoon characters, logos, comic book characters, pictures of movie stars and signers are copyrighted. This means you could get into legal trouble by using such images without paying for them or getting permission.