WHERE CAN you go to get a lunch that is always enormous, often nutritious and absolutely free? Go sit at the table nearest the kid-high disposal bin in the local elementary school at lunchtime.

At a recent lunch you could have intercepted untouched portions of hot celery soup, juice, grapes, milk, a bologna sandwich on rye, a banana, a granola bar and a box of raisins. Some of this was bought at the lunchroom counter; most of it was brought. All of it was being thrown out.

The food being thrown out was hardly junk food and the school in which it accumulated offers superior supplements to bagged lunches: Yogurt, sugar-free juices in several flavors, soup and crackers, preservative-free snacks and cheese or fruit. So why was the disposal bin filled to overflowing?

Perhaps children won't, or can't, eat well in a lunchroom setting. The circumstances aren't always ideal, though sitting in a room designed as a lunchroom is preferable to eating in a makeshift classroom. But how comfortably does anyone eat if they are rushed? Or if they have to wear or carry a bulky winter coat? Or if they sit in the midst of a hundred screaming voices and moving bodies?

Or if they know they can't wash their hands after eating?

The contents of the lunches themselves may contribute to the excess waste at the school. They may not be well prepared, or they be too much for a child to eat. A whole sandwich is often twice too much for a youngster, especially in distracting circumstances; peeling an orange is a formidable and messy task; drinking milk straight from a carton is awkward and unwieldy.

Making brown bag lunches is a time-consuming and repetitive task but it can be simplified. To prevent the entire effort from being thrown into the trash, take into account the child's capacity, preferences and delight in novelty.

If mayonnaise is rejected at home, it won't be eaten at school. Preferences can be respected and incorporated without sacrificing nutrition. If your child wants a jam sandwich every day, put the jam on whole wheat bread and mix a little wheat germ, even powdered milk, into the margarine or butter.Ask whether peanut butter might accompany the jam as well.

Send small amounts of everything: half a sandwich, cut once again, is plenty for many young children. Save the rest for tomorrow or for the baby sister at home who often wants to have lunch from a box as well. A banana is a filling fruit: pack only half, wrapped in plastic, and slice the edge a bit for easier peeling.

Make things convenient. Peel the orange or cut it into fourths and tip the points back for handles. Cut the cheese chunk into bite-size peices, or slices. Slice carrot sticks thin, or cut the carrot into coins; or send shredded carrots or carrot curls mixed with raisins.

Make a vegetable popsicle from a stick inserted into the peeled end of a cucumber.

A cut-up apple contributes to convenience but inevitably goes brown: apple slices inserted into peanut butter sandwiches aren't seen and moisten the peanut butter as well.

Remove strings from celery sticks and fill with cream cheese dipped in sesame seeds.

Variety for the child is as important as convenience. For a change, use pita bread pockets, or cheese scones, or sandwiches cut into rounds with a cookie cutter. Make flatbread with your child one day and send along a boiled egg (peeled) and cheese or peanut butter balls for protein. Make silver dollar-sized cottage cheese pancakes and sandwich apple sauce between a pair of them. Or stick half a dozen of them together for a fanciful cake.

Food balls of all sorts appeal to children and to small hands. Shred a soft cheese such as Monterey Jack and form it into balls. Add seeds or nuts if you like. Balls made from peanut butter, wheat germ, powdered milk, sesame seeds, raisins or date bits are usually well received by children and pack in nutrition as well. Send one for a friend: children love to barter and exchange.

Raisins and apricots are a good choice for something sweet, but not if they end up sitting on a child's teeth all afternoon.If you pack them, encourage your child to eat a piece of apple or carrot afterwards. A toothbrush soaked in water and encased in plastic wrap is inserted in the box of one child whose parents believe in ounces of prevention.

Cookies and cupcakes can satisfy a sweet tooth and still be nutritious. A cookie depending entirely on dates and raisins for sweetness can be frozen in quantity. Recipes for banana, nut, pumpkin and carrot breads can be made into cupcakes. A piece of oat-orange cake is a tasty treat.

Plain yogurt mixed with fruit puree and frozen is a good dessert to send. By lunchtime, the mixture is just soft enough to eat. Use stewed plums or frozen strawberries, canned pineapple or even orange concentrate for the fruit. If your child like Jell-o, cut down on the sugar and food color intake by making orange juice gelatin from concentrate and gelatin. Mold it in a styrofoam egg carton cup and tape another one over for a lid.You can use pairs of these cups for raisin and nut containers.

Don't limit the contents of the lunchbox to food alone. Try taping a different picture in the box each week: a photo of your child, or a friend, the family or even the family dog. Decide first, however, whether a picture will alleviate, or increase, the aloneness some children feel at lunchtime in school. Insert a wet wipe when the food may be messy.

Put a napkin in for those inevitable spills, or to serve as a placemat. Draw a face on it and fold it into a shape, or let your child do both.

If your child eats quickly, include a stub of crayon and a small paper plate for drawing on while the others finish. You might even include a small treasure: a picture, miniature car, a canceled stamp, or even a paper with a message in pictures or in words from you. One parent sends a cut-up postcard for use as a puzzle when her daughter is finished, another sends a paper and pencil for playing tic-tac-toe with a friend.

Making better lunches requires time. Increase the efficiency of lunch preparation by sharing the job with the rest of the family, or with the family of your child's best friend. You can exchange making lunches for two on a regular basis. Freezers are indispensable assistants: yogurt, cookies, scones, cupcakes and sandwiches can be frozen in advance. To prevent the morning rush, fix lunches in the evening and refrigerate.

If you can't pay a visit or help supervise lunch at school, ask another parent or the school what is going on during your child's lunchtime. Ask where lunch is eaten, with whom and for how long. What arrangements exist should your child forget lunch, or lunch money? What food is available for sale at the school? Is it nutritious enough to merit being sold on the school premises at all? How much supervision is provided on a regular basis? How well does your own child eat in the circumstances provided?

It is possible to believe that what is eaten both in the lunchroom and at home has nothing at all to do with what is learned in the classroom. It is possible, but hardly wise. SCONES (Makes 4) 1 1/2 cups flour 1 1/2 teaspoon baking powder 2 ounces margarine 1/2 cup milk

For raisin scones, add 2 tablespoons sugar and 4 tablespoons raisins after the fat has been rubbed in.For cheese scones, add 1 teaspoon salt and 4 tablespoons grated cheese.

Mix the flour and baking powder (and sugar or salt) together and rub the fat into the flour it is well mixed in. Add the liquid quickly and stir lightly. Do not knead but pat the mixture on a floured board and shape into a round about 1/2-inch thick. Cut into triangles, without cutting entirely through the dough. The pieces will break apart easily when baked. To obtain a smooth brown top brush over with a little milk or beaten egg. Bake on a greased cookie sheet in a 450 degree oven for 10 to 12 minutes.

These are quick, easy to make and freeze well for advance lunchbox preparation. They are also useful on any occasion when, despite having no eggs in the house, you still want something freshly baked to accompany coffee or tea. COTTAGE CHEESE PANCAKES 4 eggs 3/4 cup flour 3/4 teaspoon baking powder 3/4 teaspoon soda 3/4 teaspoon salt 1/4 cup powdered milk 1 cup cottage cheese 1/2 cup yogurt

Combine all ingredients and let stand 10 minutes or so. Make them small and cook on a griddle like ordinary pancakes until golden. Send them cold in the lunchbox, sandwiched together with apple sauce or peanut butter and jam. RAISIN AND DATE COOKIES (Makes 2 dozen) 1 cup raisins 1/2 cup chopped dates 1 cup water 2 eggs 1/2 cup margarine 1 teaspoon vanilla 1/4 teaspoon cinnamon 1 cup flour 1 teaspoon soda

Combine raisins, dates and water in saucepan, boil 3 minutes, stirring occasionally, and allow to cool. Cream together the eggs, margarine and vanilla. Sift together the dry ingredients. Add the dry ingredients to the creamed mixture alternately with the date mixture. Beat well. Chill several hours. Drop from a teaspoon onto greased cookie sheet.Bake at 350 degrees 10 to 12 minutes. CARROT CUPCAKES (Makes 12) 1 1/3 cups all-purpose flour 2/3 cup sugar 1 1/3 teaspoon cinnamon 1 1/3 teaspoon baking soda 2/3 teaspoon salt 3 eggs, beaten 2 cups shredded carrots 2/3 cups cooking oil 1/2 cup chopped nuts

Sift the flour, sugar, cinnamon, soda and salt together into a bowl. In a larger bowl, beat eggs well, add carrots and oil, mix well. Stir in flour mixture and nuts. Line with cupcake paper and fill a dozen 2 1/2-inch cupcake containers 3/4 full and bake for 25 minutes or until done at 325 degrees. A young child should have no difficulty in peeling the paper from the cakes at lunchtime. CUSTARD SAUCE 2 cups milk 2 eggs 1 tablespoon sugar 1/2 teaspoon vanilla

Heat the milk to just below boiling. Beat the eggs and sugar together slightly in a separate container and add the hot milk, stirring well. Return the mix to the top of a double boiler and cook until the custard coats the back of a wooden spoon. Stir frequently to keep the custard smooth. Flavor to taste and serve hot or cold. Care must be taken to remove from the heat as soon as it is cooked because overcooking caused curdling.

Use over bananas, gingerbread, apple pie, tinned fruit, or over anything with which you might customarily serve ice cream.

Anyone preparing food for children needs to consider the ways in which food can be enhanced without changing its character or acceptability. A person baking for children, for example, would do well to fortify the milk in recipes with additional powdered milk, to add a tablespoon or two of wheat germ to every cup of flour, to use whole wheat flour wherever possible, and to reduce the sugar to the barest minimum. A mix developed at Cornell University can be used wherever flour is called for, and increases the nutritional value whenever it is used. CORNELL MIX 6 cups flour 3 tablespoons wheat germ 1/2 cup soybean flour 3/4 cup powdered milk

One cup mix is equal to one cup flour. Store in the refrigerator.