In the average household, 6.9 meals a week are eaten away from home, says a survey conducted for ''Restaurants and Institutions,'' a trade publication for the food-service industry. For today's working couples, it seems, grabbing a burger after work has become a pleasant way of life.
Grabbing it with your kids may be another matter altogether. While some young children genuinely enjoy restaurants with their colorful straws and dependable foods, others save their most heinous behavior for the institution high chairs at the end of the day.
With a little advance planning, you may be able to prevent these 6.9 meals from turning into 6.9 catastrophes. Here are some suggestions:
Babies and toddlers. As always with this age group, you need equipment. Tote along a paper bag filled with a large bib, a bottle or training cup (filled at home or at the restaurant), a piece of soft fruit or a few crackers or cereal pieces, a damp rag in a plastic bag, and a favorite toy. This last item tends to mutate into a missile your child can use for bombarding your meal, so only bring items you think the tot may actually play with first.
The food and drink should keep your child occupied until your food arrives (maybe longer!), but then you need to be inventive. Show him how to tear napkins or use straws as drum sticks. Then there's the tour of the restaurant, the rest room, and the parking lot.
Then there's carryout.
Young children. These youngsters will probably enjoy helping you order the food, and they like talking about the pictures of potential dinners on the wall or the menus. What looks good? What looks ''yucky''?
A noise-prevention kit, consisting of a few plastic figures (to be hidden around the ketchup bottles and sugar bowl), or a book of mazes, or dot-to-dot drawings, and a pencil may give you time to talk with your spouse before the food arrives. If you have two young children, they might enjoy playing card games together.
Restaurants have other built-in preventatives for kids, such as:
* Sugar cubes. These can be converted to dice with a pen, putting one dot on one side; six dots on the opposite side; and two, three, four, and five dots around the side.
Just trying to figure out the number of dots on one die is enough of a challenge for a very young child, but those more experienced in math can try adding the dots on two, three, or four sugar-cube dice thrown at once; multiplying (two dice); and seeing who can roll the highest number, the lowest number, or a number that is a multiple of two or three.
* Toothpicks. Grab a dozen as you walk in, and ask the kids to make a pentagon, a hexagon, an octagon. How many sticks do each require? Try making everyone's initials, the word ''no,'' the word ''yes,'' all the letters of the alphabet (one at a time), the numbers up to 100. You have to pay attention during all this, but it keeps them quiet.
If you can get the toothpicks away from your child, put them in a pile and hide six in your hand. Then ask how many you took away from the pile of 12, and see if the child can figure it out. Take turns. You can vary the number in the original pile - try two piles of six, or a pile of eight. How many different problems can you make up?
* Straws. Here's how to make a ''snake'' that grows, using a straw cover: Carefully tear the top of the paper cover, and scrunch the cover evenly down to the bottom of a straw. This is your snake. Now, use the straw to get a little liquid from your water glass (any liquid will do), and drizzle it, one drop at a time, on the snake. It should start to grow.
Older children. This age group is rarely a problem, but if you have a particularly long wait, here are some suggestions:
* Menus. Give the child some paper and a pencil, or a pocket calculator (if you carry one) and ask him to figure out the total price of your meal, including tax, if appropriate. What is the average price? Who came closest to ordering the average price? What should you leave as a tip?
If the math seems overwhelming, ask him to pick out the most and least expensive items on the menu. How does he think the restaurant decided on that price?
Menus are often treasure-troves of adjectives and adverbs. Ask your child to find the most adjective-laden description. Are all of those terms necessary? Which are the most unnecessary (our favorite is ''country-grown'')? Can he compose a more straightforward description? An awful description of a favorite food (''ground-up meat placed between two chemical-laden buns with limp lettuce and tired tomatoes,'' for instance)? A delicious description of a disliked food (''succulent liver . . .'')?
* Decor. Restaurants must choose furnishings that soothe their customers, stimulate their appetites, and stand up to hard wear. What does your child think of the color scheme? The pictures? The tables and chairs? Why were they chosen? What would he change, if he could? What would an ideal restaurant look like? What food would it serve? Where would it be located?
* Careers. How many different kinds of jobs are involved in running a restaurant? What kinds of work are done in each of these? Is it the kind of work he or she would enjoy? What are the problems and advantages of working in a restaurant? Who does the most work? Who is paid the most?
Finally, if you're truly desperate, here are three lifesavers to try with kids over two years old:
* The Quiet Game. See who can be quiet the longest.
* The Chewing Game. See if you can chew each bite 20 times (or 10 times, if your child can count that high).
* The Trash Man. See if you can stack all the trash on one tray so it doesn't fall.