Decide upon the history topic that you are teaching. Create a preliminary plan for teaching, outlining topics that you need to cover to adhere to state standards.
Talk with colleagues that teach other subjects. Collaborate with peers to find out what they are teaching and what standards students need to learn for their subject. Tell them what you are teaching and gather ideas of integration topics from their subject. Ask them if they would be willing to coordinate their lesson plans to teach on the topic during their class. If you are studying World War I, talk with the Language Arts teacher about introducing "The Diary of Anne Frank" into her lessons.
Create your lesson plan to include integrated subjects. Now that you have spoken with peers and gathered ideas, you can create a formal lesson plan to include integration. One idea is to teach on the Great Wall of China and integrate math and science, talking about any math principles that were included in construction and durability of the wall and materials used for sustainability.
Deliver your lesson to students. Pay attention to adding activities that include all three learning styles: visual, aural and kinesthetic. This will accommodate all students and help to keep them engaged in the material.