Prominently display the numbers in the classroom, preferably in the front of the room.
Count through the numbers while pointing at the corresponding number on the display. Ask the children to repeat after you as you recite them again.
Choose a song to use for your students. Look through educational reference books or online for appropriate songs, or come up with one of your own.
Play the song and ask the class to listen the first time. Point to the display as the numbers are sung.
Play the song again and sing along this time, encouraging the students to sing as well. Play the song several times through, always pointing to the numbers on the display.
Continue with class activities, but each time numbers are mentioned throughout the day, begin singing again. For example, if a student says, "I like that, too." You say, "Too? Two? Monkey one and monkey two, Monkeys do the hula hoop!" or whichever number song you are using. Making it fun or comical will not only help with retention, it will make learning easier.
Play the song each day. Allow the students to get up, move around, and dance as they recite their numbers.
Supplement the song with crafts and activities that focus on numbers. Once the children have learned their numbers continue using the song as a review.