From my experience here in Japan, students are taught the numbers up to twenty, then "thirty", "forty" etc up to a hundred and then pretty much left to fend for themselves. When I asked some students how old they were I noticed quite a few counting from one to the number they needed. So here are some activities to help them become more familiar with English numbers 1-100.
5. Danger Number
You need: nothing
To play: Put the students into pairs or small groups of three or four. Decide on a "danger number", for example: 100. The first player starts at "one" and may say a maximum of three numbers. If he says "one two three" then the next player will start at "four" and again may say a maximum of three numbers. They keep going until one student is forced to say the danger number and is out. If you are playing in groups this can either be the end of the game, or you can play another round with the out player rejoining, or you can play the next round with only the remaining players until you have one final winner. This is good as an introduction to other games as here they are still using the numbers consecutively.
4. Board Game
You need: A board game template, dice
To play: Fll in the template with various sums using plus, minus, times and divide (assuming your students are old enough to do this in L1) you can either write digits or write the sums out in words. When a student lands on the sum they must read it and give the answer. Add variation with "roll again" or "go back three" squares.
3. Sums Bingo
You need: bingo papers
To play: Have a list prepared of the numbers on the bingo papers and corresponding sums. Be careful not to duplicate any numbers. You will call out a sum and the students must find the answer. Be aware that some students may merely be finding out the answer from other students, ask them to play quietly.
2. Word Sums Read'n'Run
You need: Sums written out in word form. Memo paper or worksheet for each pair
To do: Pin up the word sums around the room. In the pairs one student will run to the sums and run back to report to the other student who will write down the sums. They can work together to find the answer. You can have them write down the words but I find it's better to have them write down numbers, that way you know they understand.
Variations: To make this harder instead of writing sums as "two plus four" you can write "the number of eyes you have plus the number of legs a cat has" (free download will be up by the end of this week!)
1. Playing Cards Plus
You need: one deck of playing cards between each pair, could also be done with small groups of three or four if you don't have enough cards
To play: Each student has half the deck. At the same time they put down the top card face up. The first student to add up the numbers and say the total gets to keep the cards. This is a very simple game but it allows the students to think of the numbers independantly and to speed up their thinking. If you have groups either split the deck four ways and play in pairs or have the students take turns flipping two cards and all students compete to call out the answer.