Last week I found great ideas, worksheets and links for Christmas activities. Today while I was adapting one of them for my class, I came across with wordsmith.org. The site helps you find hundreds of anagrams for the word or phrase you have chosen, then even it animates the anagram and even allows you to choose font, text and background colour.
You can download the worksheet and use in your class. You can find more worksheets on christmas vocabulary from