Haha This is the exact situation I walked into this past Friday!  I also want to thank you guys for the good advice and resources. 

BTW - Do you think games like london bridge and ring-around-the-rosie are educational enough?  I tried simon says but that was a disaster.  I guess the rules were too complicated when only explained in English.

You need to lay down the rules with them first, as young as they may be.

Try this & they'll soon get into the habit of it. If they're running a riot, just stand at the front, and hold up your index finger. They should clap once. Hold up 3 fingers. They should clap three times. Do this a few times - holding up 1, 2, 3, 4, 5 fingers and they should clap accordingly. When you show them zero, they don't clap and there should be silence.

Always start with a song. Even thought I have a co-teacher for my Kindergarten class that I teach once a week, I start off with the "Hello" song from Junior Naver. This is great, because it becomes routine and they will expect to sing it at the beginning of every lesson.

Use candy, stamps or stickers. At random, choose one or two kids who are exceptionally well-behaved, are being active during activities and doing their work well. Bring them to the front of the class and reward them in front of their friends.

Since it's an after school class, minus points won't work well. Rather, reward them!

With YL's, remember you become an entertainer! Teach them songs with actions like "Head, shoulders, knees & toes / Eensy Weensy Spider / Hokey Pokey / Skidamarink"

I start all my YL's with parts of the body. This can take a few lessons to cover. In the first lesson, you may only just be able to cover "eyes, nose, ears, mouth". Drill this in and then add maybe two more.  I have a great activity for this that they love. All you need are crayons and paper. Let me know if you'd like it.

Otherwise, give the other suggestions a try and let me/us know how it turns out:)

Review worksheets.
 
I don't have specific ones in mind, but you can search the net for all sorts of stuff. For the 1s and 2s I suggest dot-to-dots (simple and self explanatory), or games that can be played with a partner, such as tic-tac-toe. With the older kids wordsearches and crosswords are a great way to keep them busy while you help the lower level kids.

I have also found that older children enjoy coded messages. All you need to do is create a key where a different letter or symbol represents a letter of the alphabet and type out the sentence in code. The kids then have to figure out what the secret message is.

Another way with dealing with kids who move faster than the rest of the class is to do it together. Make sure you get the whole class involved on the task together. That way if the low level kids don't know what is going on the can see from example what should be done. Move around the class getting different students to answer the questions or problems, normally a low level kid will never raise their hand, so simply ask them what the answer is once a high level kid has already given it and check that the low level student is doing the right thing. If you do things as a class it ensures that tasks are finished at the same time and means you don't have to explain things more than once.

here is another site I have been using for my 1s and 2s
http://www.tlsbooks.com/kindergartenworksheets.htm

Oh, games. Lots and lots of games. Once the kids find ones they enjoy, keep those games for the end of the lesson as a carrot.

Simple ones work best, although anything too physical like Simon Says can get messy if your class isn't well-behaved.

Try stuff like:
> Fruit Basket
> Bingo
> Card-slap/snatch game in groups
Kids get little cards and the sit in groups and slap the one that you say out. First to slap it wins the card. Give them hands on heads ready positions as a clear rule. Great for revising or teaching numbers as everyone counts their cards together afterwards.
An alternate version is a big card-slap game. Use big flashcards on the board and they line up in little queues behind a line. Get little flyswatters for the team leaders to race to slap the flashcard you yell. Then they pass the swatter on and go to the line's end.
> Whispers/Telephone
Politically-incorrect whispers.
> The ticking bomb game
Put an egg timer in a box, pass it around using target vocab or expressions. When it goes off, that child is "unlucky" but doesn't really lose anything.
> Western gunslinger duel
Two teams, team leaders stand back to back and are each given ~secret~ flashcards to hold to their chests. On your mark they take three big steps, spin around. The first to yell out whats on the opponent's chest-flashcard shoots first and wins their team a point. And a sticker or something.
> Letter tracing
Sing the alphabet song and show flashcards. Now, line children up in teams. Trace a letter on the final child's back. They trace it on the next and so on. Front child eventually draws it on the board.

To ensure you're not remaking materials, or left high and dry if one child plays up, young grades are something I'd advocate heavy, wasteful use of a laminator if you have one. Thats right, I'm saying laminate bingo boards and give them counters. Im saying laminate slap/snatch cards (but trim the corners because they will impale thier hands!). Laminate the trees, laminate the whales, laminate your own face if you have to, y'know?

For the second graders, try asking for two student leaders (Is volunteer a loan word in Korean? I suspect it may be, so they may know that. For young learners, you _can_ sometimes use loanwords as a crutch to push instructions.) and reward them with stickers or something. When explaining a game, demonstrate with them. Literally just kinda relocate them around like chess pieces to explain if needbe.

For safety, in any high energy game, I'd consider getting the student volunteers to become Ministers for Silly Walks and come up with a "funny super special walk" for the day, that the students must mimic. The goal is something so utterly disjointed (think horrid Elaine dance from Seinfeld level) that its IMPOSSIBLE to funny-walk and run at the same time. Do this even for games like whispers.

For discipline, I've seen some elementary school teachers exaggerate their expressions to Jekyll and Hyde levels and it works hey. Smile a stupid amount, but as soon as something is not ok, show it clearly. Even if another teacher is assisting. Then switch back to stupidly happy the second its over with a big cheery "OK!"

My best luck with younger grades came from a well structured lesson plan each time.
In this case, the kids first sung a few warmup songs including a standard "Hello Song" every lesson, one related to their current target language, and a revision one. A very good idea from one of my former co-teachers was to ensure one song at the start was really energetic. Like Head, Shoulders, Knees and Toes, or any song with the kids making actions up. This burnt them out so much they were ready to collapse and listen. Once you teach a song, be sure to get the kids to sing it again next lesson, and the one after, and the one after that etc. Drum it into them because they'll get satisfaction out of being able to show off their knowledge.
Moved on then to flashcards and the like (d/l from mes-english, can't recommend them enough!). Make the cards fun, hide cards and slowly reveal them, put surprise ones in the deck that they know (like Korean foods), vary your voice and get them to mimic.
Finally, a game or activity.
Lesson split in thirds. The kids came to expect it that way, let's you control energy levels.

Storybooks work very well if you can get them settled, thats 1/3 of a lesson there.

Finally, ensure they have name-tags. Younger grades respond extremely well to learning their names. If you have too many to remember, the tags work wonders. Plus, without tags, how will you ever learn? "English names" (shudder, pet peeve of mine!), romanised Korean names or Westernised abbreviated Korean names, all are good.

To translate things, use images as a medium, or use the phrase "Whats that, in Korean?" and pick a student. You may find some know and can be your translator for tricky stuff.


Sorry about the long messy list type post, but I hope theres something in that mess that helps someone! Personally, I miss teaching the 1sts and 2nds, my spot this year is 3rd and up. I almost find the younger ones easier to work with, simply because you can see what they learn and build on it easily. Planning can be methodical. Progress may not be fast, and the lessons can be rather trying, but its very obvious when they do improve, and that sort of feedback makes for a rewarding job! :D

I've 2 kindy classes in chungbuk starting next wk, when I taught that age in Taiwan last yr I found they love to run around!
So, I made it into a hide and seek game with objects, letters, phonic sounds.
Also, I'd bring in a big hammer and let them hit objects, themselves, others...
Another great one was getting them to form letters from their bodies on the floor, have two or three sts making a 'T' or 'J' shape, or if they're really smart 'A' and 'B' - they're difficult!!
As much kinesthetic stuff you can manage, and I'd always finish with a story. Any big book with lots of pictures where they can make the story up along with narration.

I just started teaching kindergarten this semester and have been really enjoying it, although today the students went kind of crazy and I had no way to control them.  I only see each class once a week for 40 min. so that makes it challenging too. I tried using a reward system, but that didn't really work.  They were just rolling all over the floor, jumping on each other and grabbing my flashcards, haha, wow what an hour!
I was wondering if anyone had advice for this age students regarding classroom management.  If I keep going this way the only thing they will learn by the end of the year is "Be quiet!" 
Any advice would be appreciated!  Thanks!

I also teach kindergarten for 40 mins. but I broke it up into two 20 min. classes.  It's way too hard for them to see there and concentrate for 40 mins even if you have many activities.  Try and see if your school will let you do this.  You can tell them it would be better cause that way the students get to see you twice a week instead of once and you can better review witht them what you taught the first class.

Barring that you have to teach them a chant with gestures so they will know if they are being loud and not paying attention when you tell them "clap, clap clap" or whatever you use.

Thanks for the advice!  I really appreciate it and will hopefully get going on a better foot with this class. 

with this age group there is a lot of singing, laughing; action type games and after all the chaos hopefully they learned something!

If you have a coteacher ask them to help you teach chants so that when they're not there you can still get their attention. My homeroom kindergarten teacher uses loads of chants (Korean) with her kids and they are extremely receptive.
Hope it helps!