Young students like this activity, and when you do it in English, they will practice position vocabulary without effort. Here are some pages recommended by Michèle Henry, ou colleague from Nancy-Metz
http://books.guardian.co.uk/posysimmonds/page/0,12694,962103,00.html (difficult)
http://www.auspacmedia.com.au/images/features/defaults/144.gif (with solutions)
http://www.primaryresources.co.uk/english/xmas.htm (class situation to comment upon!)
http://www.4to40.com/activities/quiz4u/index.asp?article=activities_quiz4u_spotthedifference1 (easy, plus type the answers and read if you spotted them right.)
