I have 4 after-school classes a week, each 45 minutes with no co-teachers.
Grade 1 = 7 students = Game / Reading / Game
The students are low level so the games are good to keep their attention and the reading acts as the learning stage of the lesson and keeps the students focused. I have the students read one sentence each of a mini-story (
http://www.rong-chang.com/easyread/) which I cut down to two paragraphs, anymore and the students really struggle. It's important to end the lesson with a fun activity to keep them engaged for the next lesson in my experience.
Grade 2/3 = 13 students = warm-up / reading / listening / activity.
I am fortunate that for the most part that these students actively want to learn and the smarter students in the school. Those in the class with a lower ability are normally friends with a higher ability student who I then encourage to help their lower level friend.
I start with a quick game every lesson called 'minute to win it'. Put students into 4 teams. Each team takes a turn writing as many words on the board in 1 minute. Each word must start with the previous word's last letter (e.g. water > rat > tree). Students must write words alternatively in their team and are rewarded one point for each letter used (hence encouraging the students to use longer words). Once the students learn the format of the game they very quickly start to use bigger and better words, each week bettering the previous high score. It's fun, quick, get's them thinking and most importantly competitive which they obviously love.
Then I do a reading exercise on the relevant week's topic (extreme weather, money, travelling, endangered animals etc.) and try and fit in a game at the end relevant to each topic.
The best game I've used (found on waygook) is called 'Making money' :
http://www.eslcafe.com/idea/index.cgi?display:1003716375-11849.txt.
Essentially students have to make the most money in 20 minutes but face various problems along the way. The game leads on nicely to a number of different lessons such as politics, supply and demand, natural resources or countries.