Each week or month assign a specific color, letter or group of letters and number for the class to focus on. You can practice counting to the specific number or writing the letter. Students can also complete several art projects that focus on the color of the week or month.
Students can learn to observe things using the five senses. This theme would have several circle times that talk about a specific sense. You can have center time at which students touch, taste and smell a variety of items. Additionally children can play games in which they focus on a specific sense, such as "telephone" for hearing.
Focus on farm animals and activities this week. Sing the song during circle time and have students act like the different animals. Additionally, they can count the number of animals in each section. Crafts can include creating different farm animals. There are several wonderful books that talk about life on the farm.
This could be broken into four different week-long units that you disperse throughout the year. For each unit read books about the current season. Students can go on nature walks to observe the changes in the plants and animals during the season. Crafts could reflect specific characteristics of the season. For example, create leaf collages in fall, snowflakes and snowmen in winter, leaf rubbings in spring and sun crafts in summer.
Create a unit based on several books by Dr. Seuss. This unit would focus on the stories, and you can create a craft that is related to each book you choose. You can also incorporate parts of the stories into other areas. For example "There's a Wocket in My Pocket" is an excellent book that helps children to understand rhyming.
Create a unit based on friendship. Read books about making friends and including others. Crafts can be gifts to give friends. Children may also draw a picture of themselves with a close friend for the bulletin board.