Building classroom activities and materials around a thematic topic is a wonderful way to get children excited about learning and to connect the different areas of your curriculum in a meaningful, integrated way.
Thematic instruction is based on the idea that children (in fact, adults too!) learn best when instruction is presented in the context of a coherent "whole," and when they can connect what they're learning to the real world. Thematic instruction provides opportunities for children to make connections among different subject areas (such as reading, math, and science) and to build a base of knowledge about a particular topic. The teacher chooses a thematic topic and then chooses lessons, books, and activities that relate to the theme. A thematic unit may be designed to last for a week, a month, or even longer. Most teachers change themes every few weeks or so.