DH and I eat a lot of rice, and to get more whole grains in our diet I wanted to slowly introduce brown rice into our diet. I found that the easiest way to do this is to cook both brown and white rice together (even though they have different cooking lengths). I used the following method, at first using a 75% white rice to 25% brown rice ratio and we've worked our way up to 25% white and 75% brown. This method is shown using 1 cup total of uncooked rice with a 50/50 ratio, but I've made up to 3 cups of mixed uncooked rice in this way (increasing the water proportionally, of course).
2-1/4 cups boiling water
salt, if desired (I use 1/4 tsp)
1/2 cup brown rice
1/2 cup white rice
Bring water & salt to a boil in a covered saucepan.
Add brown rice and cover.
Turn heat to low and let simmer for 12 minutes.
As quickly as possible lift the lid and sprinkle the white rice evenly on top of the brown rice and replace the lid (this will get easier as you do it more often).
Turn the heat to medium for 30 seconds, then back to low.
After 12 more minutes, quickly peek under the lid. There should not be any bubbles around the edge or coming up from the middle of the rice. If so, relpace the lid and let cook for a few more minutes and try again. If not, replace the lid, let simmer for an additional minute, and turn off the heat.
Let the rice sit for 10 minutes.
It sounds a bit complicated, but I developed this method because I didn't want to use two pans to make the both types of rice separately. I'm usually in the kitchen anyway as this cooks, so as long as I remember to set the timer, it works out just fine!
edited to say that after doing this several times, you'll be able to listen instead of peeking to check the water level (after the second 12 minutes) to determine if the rice is at the appropriate stage of cooking. It's kind of a "dryish sssssssssss" sound.