I do this every morning. 1 part oats to 1 1/2 parts water in a glass/ceramic bowl that is at least twice as large as that volume. I microwave on high for 2 minutes. I typically use between 1/2 to 2/3 cups oats in a large cereal bowl. Usually the oats will boil up to the rim of the bowl just before it's done. Lower wattage microwaves will probably take longer. Watch for the oats to boil up so they don't spill over. Usually once it's got a good dome to it then they're done enough. I've got mine down to a science. I then add my raisins or banana, some cinnamon and about 1/8 to 1/4 cup milk, stir, and let sit for a couple minutes to absorb the added liquid.