1. Biographies of scientists and mathematicians can be part of your reading courses.
2. Teaching Science with Tradebooks is an excellent resource; if your students are older, find otu what chapter books they are reading, and see if their are lessons incorporating science, social studies, etc. I would collaborate with the language arts and social studies instructors, find out what they were doing, and connect as best we could. I have used Endurance: Shackleton's Incredible Voyage to study geography, nutrition, caloric intake, weather, oceanography, and even ship building. PBS has a plethora of resources as well, NOVA specifically. I have used the Iditarod to again teach mathematics (mileage, speed, caloric intake), physical science (motion, friction, weather (winter storm paths, how to surive in cold weather), Nutrition (food as fuel and building blocks (Chemistry in the Community helped me with this) for humans and animals), Materials Science (materials for sleds, colthing, other gear), and I have added other intersts when students ask. Winterdance by Gary Paulsen is a great read about training for the Iditarod as well.
3. Doing a science lab, graphing data, organizing data for patterns, all connect to mathematics.
4. In mathematics, I would do hands on activities that were often science labs, but focus on the data itself, how to organize it, how to display it-graphing, even finding equations that fit the data. In Algebra 2, I often used the spreading of a common cold, wehere we would do a variatio of the labs below, collect the data, then calculate the equation that best fits the data of a group, the class, and then I had multiple years of data, for that larger data set.
You can use the book Outbreak as a reading enhancement, or ther books that might be more appropriate for a different grade level.
5. The geography teacher would often talk about disasters caused by humans-such as the Bhopal gas tragedy; as a science teacher I would hep the students wtih the science and understanding how it could have happened, the geography teacher would talk about the social impacts. Natural or human disasters give relevance for learning more in contents, allows for itnegration.
6. I borrowed argumentative essay guidelines from the language arts instructor so students would be following the same or similar writing guidlelines for reading news stories, journal articles, even their graphic organizers. So collaborating with other content teachers really ehlped me at the HS level.
Hope this gives you some ideas and a start at integrating!