Dear Martha: Is a wooden or plastic cutting board better? What about bamboo?

A: These can all be good choices, as long as you clean them properly. Plastic is lightweight, so it's easy to handle, but it is more likely than wood to dull the blade of a knife. Wooden boards are attractive enough to leave out on the counter, as are those made from bamboo, a grass with rigid stalks that can be glued together into planks. Bamboo is very hard and does not scratch easily; it's also a rapidly renewable resource and an environmentally friendly option.

The U.S. Department of Agriculture recommends reserving one cutting board for raw meat, poultry and seafood, and another for fresh produce and vegetables. This way, you won't contaminate food that will not be cooked with bacteria from meat.

You might also devote a separate board to aromatic ingredients, such as onions and garlic, to avoid transferring their odors to other foods. If you use plastic boards, opt for ones in different colors. This way, it will be easy to remember which foods you've designated them for.

Because cutting boards can harbor bacteria in the grooves created by knives, it is imperative that you wash them thoroughly with hot, soapy water after each use. Plastic boards may be cleaned in the dishwasher; bamboo and laminated wood should be scrubbed by hand.

Manufacturers say solid wooden boards are dishwasher safe, but the heat and moisture can dry them out, so you'll need to oil them frequently if you put them in the dishwasher. Replace heavily scarred cutting boards with new ones.

Dear Martha: Why do my cakes fall in the center?

A: Cakes collapse for a variety of reasons. Sometimes the oven is too hot: The outside of the cake cooks more quickly than the middle, which falls because it is underdone. If the oven is too cool, the results can be uneven as well. Use an oven thermometer to see if your appliance's settings are accurate. And always check cakes for doneness with a toothpick.

Baking is a science, so make certain you measure ingredients accurately, and never substitute one ingredient for another without making the right adjustments. This is most important when using baking powder and baking soda. When mixed into batter, these chemical leaveners produce carbon dioxide, which makes tiny bubbles in batter expand and rise, adding volume and lightening the texture of the cake. Too much or too little of either leavener disrupts this process and can result in a cake that does not rise properly.

Check the expiration date on baking powder and baking soda before using them. Even better, mark the date of purchase on these products and replace them twice a year. Changes in temperature and extreme humidity can decrease their potency.

Keep flour fresh by storing it in an airtight container. Finally, modify your recipe if you live at an altitude of 2,500 feet or above. Higher elevations have less atmospheric pressure, which affects cakes and other baked goods. *

Questions should be addressed to Ask Martha, care of Letters Department, Martha Stewart Living, 11 W. 42nd St., New York, NY 10036. Questions may also be sent by electronic mail to: mslletters Please include your name, address and daytime phone number.