If you want to make the game a little more challenging after they have gotten used to writing the dates down, here's a game that I've used with both Junior High School students and 5th/6th grade elementary school students that's usually a hit, even with those not too energetice classes.
Prep:- find a one-page calendar of the year (you can find one on the back page of most calendars). Make enough copies so that each group of 4-5 students will have one. Now make a list of famous dates in that year, most notably public holidays, teachers' birthdays, etc.
Playing the game:- put the kids in groups. have them decide in their groups who will answer 1st, 2nd, etc. Have the 1st person in each group stand up. Call out a holiday/birthday/etc., the first student who can either call out the correct date (or you can have them race to the board and write it) gets a point.
A variation is to have the person stand at the board and his/her teammates have to call out the date and they have to write it.
Another variation I stole from Japanese game shows- once the student figures out the date, they have to come up to one of the teachers and whisper it to the teacher. If they're right, they get some points- the first team gets 10 pts, next gets 9, etc. If they're wrong, they can go back to their group and come back and try again. Personally, I like this version the best because it keeps the kids involved even after the fastest team has finished- they still have a chance at some points!
Since I'm in Japan, I tend to use the Japanese holidays to start, and then progress to Canadian ones to "level up" the game once it's going...and the teachers' birthdays are always worth extra points (but we usually have to give some hints)!
