IT'S NOT always easy for parents to encourage children to cook. For one thing, kids tend to be messy, for another, they want things explained that are not always easy to explain. The messiness is something you either learn to tolerate or you don't. If you're patient and lucky, it diminishes as time goes by. As for the explanations, it helps to give children cook-books geared to them.

Because children don't always react to cookbooks the way grown-ups expect them to, we've listed some of the more interesting cookbooks on the market now, with comments by 10-year-old Romi Mancini, who tested recipes from most of them.

* "Better Homes and Gardens New Junior Cookbook" (Meredith). A great present for a kid who is just starting, free of errors, with excellent directions. "I'm using more complicated cookbooks now, so this has become kind of simple to me, although it isn't as simple as some books."

* "The Great Pumpkin Cookbook" (with Peanuts characters, Determined Productions). A very good cookbook, with cartoons illustrating the recipes. "It has all kinds of sweet things in it."

* "The Kid's Cookbook" by Patricia Barrett and Rosemary Dalton (Nitty Gritty Productions). Simple enough for advanced beginners, even for small children with just a little bit of experience. Recipes use few ingredients and are suitable for stubby little fingers. "It's very simple for a 10-year-old. Recipes taste like they are made by someone who can really cook."

* "Life With Working Parents" by Esther Hautzig (Macmillan). A terrific book with more than good menus, it also instructs children on how to deal with non-cooking emergencies.

* "The Campus Survival Cookbook Number 2" by Jacqueline Wood and Joelyn Scott Gilchrist (Morrow). While this was written for college students, children also appreciate it. Recipes can use some touch-ups, but are easy enough for 10-year-olds. A terrific book, and the title suits it. "You can really survive on this food -- this is decent."

* "How to Survive When Mom's Away" by Jeff Sargent, Scott Hicken and James Bybee. Written by three Boy Scouts, this book was a big success for a mail-order book. A success at our dinner table, too. (To order, send $3 to Jeff Sargent, 669 Argonaut St., Manteca, Calif. 95336.)

* "The Wonderful Wizard of Oz Cookbook" by Monica Bayley (Macmillan). Although some of the recipes are delicious, this cookbook is not very well written and includes errors in a few of the recipes.

* "Many Hands Cooking" by Terry Touff Cooper and Marilyn Ratner (UNICEF and Crowell). A beautiful international cookbook that parents love. But children may be less enamored of the unfamiliar dishes and combinations. "I made groundnut soup from Nigeria for my Girl Scout cooking badge, and I didn't like the way vegetables tasted with peanuts."

* "Kids Cooking" by Aileen Paul and Arthur Hawkins (Doubleday). A beginner's book with simple recipes for familiar dishes like meat loaf, spaghetti and french toast.

* "Cup Cooking" by Barbara Johnsonn and Betty Plemons (Early Educaters) seems to be for parents and teachers to use with kindergarteners; certainly it is for very young children.

Here are some cookbooks that seem to please parents more than children:

* "Science Experiments You Can Eat," "More Science Experiments You Can Eat," and "Arts and Crafts You Can Eat," all by Vicki Cobb (Lippincott), and "Creative Food Experiences for Children" by the Center for Science in the Public Interest. They are books best for parents and children to use together. " 'Arts and Crafts' took too much patience and time, and the other books were too scientific to enjoy."

* "Knead It, Punch It, Bake It!" by Judith and Evan Jones (Crowell). Neglects details such as preheating the oven. "The blueberry muffins were only so-so."

* "The Little House Cookbook" by Barbara Walker (Harper & Row). Pioneer-type recipes, from the era of the Laura Ingalls Wilder books. "The cornbread we made was so dry we couldn't eat it."

* "Super Heroes Super Healthy Cookbook" by Mark Saltzman, Judy Garlan and Michele Grodner (Warner Books). A health food theme lightened by cartoons and funny titles like "Crack a Joke Popcorn." But what the book teaches is that healthy food does not necessarily taste good.

* "Peter Rabbit's Natural Foods Cookbook" by Arnold Dobrin (Warne). Parents find this book sweet, but children may balk at the likes of orange-honey carrots. "Who wants to eat a vegetable sandwich?"

* "The Taming of the C.A.N.D.Y. Monster" by Vicki Lansky (for parents, Meadowbrook Press), makes healthy food sound good. "Maybe they just give their recipes better titles."

* "The Kids' Diet Cookbook" by Aileen Paul (Doubleday). The dish we tried didn't work; the fillet of sole was so overcooked, "it curled up right away and fell apart."

While all bookstores are likely to stock some children's cookbooks, most of these are available at two children's bookstores: The Cheshire Cat (5512 Connecticut Ave. NW, 244-3956) and Junior Editions (in the new part of the Columbia Mall, 730-BOOK).

Here are recipes for two meals and a snack, from the children's cookbook shelf.

FRESH FRUIT SALAD (4 to 6 servings)

This recipe is fun to do, but takes time. The secret to making round melon balls is to place the melon baller rounded side up on the melon, push it down as far as you can and then turn it around (otherwise you only get half a ball). 1 cantaloupe 4 bananas 1/4 watermelon (optional) 8-ounce can pineapple chunks Any other fruit you want to add 1/4 cup orange juice 1 tablespoon sugar

Cut the cantaloupe in half and clean out the seeds. Using the melon baller, try to scoop out as many melon balls as possible. Put in a bowl. Do the same with the watermelon. Add the whole can of pineapple chunks with the juice. Peel and slice 4 bananas and add. Add 1 tablespoon sugar and 1/4 cup orange juice. Mix all together and serve. Tastes better if it is in the refrigerator for about 1/2 hour before you eat it. From "The Kid's Cookbook"

EGG, CORN AND CHEESE PUFF (4 servings)

A little like scrambled eggs, except one out of every four bites you get a terrific mouthful of cheese. 6 eggs 3/4 cup milk 1 teaspoon salt 1/8 teaspoon pepper 1/4 teaspoon dried basil 1 teaspoon dried chopped parsley 1 cup canned whole-kernel corn, drained 1 cup cubed cheese, such as swiss, cheddar, muenster or a combination of all of them 1 teaspoon butter

You will need: large bowl, whisk or fork, measuring cup, measuring spoons, can opener, sieve, small bowl, spoon, knife, paper towel or napkin and a baking dish or casserole.

Preheat the oven to 350 degrees.

Crack the eggs and put them into a large bowl. Add 3/4 cup of milk to the eggs in the bowl. Beat the eggs and milk with a whisk or fork to mix them well.

Add 1 teaspoon of salt, 1/8 teaspoon pepper, 1/4 teaspoon dried basil and 1 teaspoon dried chopped parsley to the milk and egg mixture. Beat again with whisk or fork.

Open the can of corn. A 1-pound 1-ounce can has more than you will need. Put the sieve over a small bowl. Pour the contents of the can of corn into the sieve. Using a spoon, take out enough drained corn from the sieve to fill one cup. Add the cup of corn to the egg and milk mixture in the large bowl. Mix with fork or whisk.

Put the remaining corn in the sieve into the small bowl with the corn juice. Cover and refrigerate for use later on.

Cut up enough swiss, cheddar or muenster cheese chunks, or a combination of all three, to fill one cup. Add the cheese to the mixture in the large bowl. Mix with fork or whisk.

Butter a baking dish or casserole. If you have never buttered a baking dish, here is what you do. Put 1 teaspoon of butter on a piece of clean paper towel or on a paper napkin. Rub the butter all over the bottom and sides of the baking dish or casserole. This will prevent the mixture from sticking to the dish.

Pour the egg, milk, corn, cheese, etc., mixture into the buttered baking dish or casserole. Bake for about 40 minutes in the oven, or until the top is puffy and golden brown. From "Life With Working Parents"

AUNT EM'S CHICKEN AND DUMPLINGS (4 servings)

This recipe is for an advanced beginner or better. 3- to 4-pound stewing chicken, cut into serving pieces 1 large onion, stuck with 2 whole cloves 1 large carrot, cut in half 2 stalks celery, cut into 3-inch lengths 2 sprigs fresh parsley, or 1 dried 3 cups water 2 teaspoons salt 1/4 teaspoon pepper 4 tablespoons butter or margarine 3 tablespoons flour 1 cup milk

Dumplings: 1 cup flour 1 1/2 teaspoons baking powder 1/2 teaspoon salt 2 tablespoons chopped fresh parsley 2 tablespoons shortening 1/2 cup milk

Put chicken, onion, carrot, celery, parsley, water, salt and pepper into stew pot. Cover and simmer for an hour or more or until chicken is just tender. Skim fat off broth and discard. Melt butter in a frying pan. Add flour, stirring constantly. Add milk slowly while stirring. Cook and stir until smooth and slighty thick. Add to broth and remove from heat.

To make the dumplings, put flour, baking powder, salt and parsley into a mixing bowl. Add shortening and mix lightly with your fingertips to blend the mixture until it resembles coarse meal. Add milk, stirring with a fork, until well mixed. Bring stew to a boil over medium heat. Turn down heat. Drop dumplings from a tablespoon onto the top of the simmering broth. Cover tightly and cook 12 minutes. Do not remove cover while steaming dumplings. From "The Wonderful Wizard of Oz Cookbook"

YOGURT MUFFINS (Makes 12 muffins) 1/4 cup melted margarine 2 cups biscuit mix 1/4 cup sugar 1/2 teaspoon baking soda 1 egg 8-ounce yogurt, any flavor

You will need: small saucepan, large bowl, wire whip, muffin tin, paper liners, measuring spoons, measuring cups.

Turn oven to 400 degrees. Put margarine in saucepan to melt at medium heat.

Stir together in a large bowl: biscuit mix, sugar and baking soda. Add egg, yogurt and melted margarine, whip until well blended.

Line muffin tins and pour batter into tins, filling 2/3 full. Bake about 15 minutes. From "How to Survive When Mom's Away"

SNICKERDOODLES (Makes about 36) 3/4 cup sugar 1/2 cup butter or margarine 1 egg 1/2 teaspoon vanilla 1/4 teaspoon salt 1/4 teaspoon baking soda 1/4 teaspoon cream of tartar 2 tablespoons sugar 2 teaspoons ground cinnamon Shortening

In a large mixing bowl cream the 3/4 cup sugar and the butter or margarine with a wooden spoon. Beat in the egg and vanilla.

In a small bowl stir together flour, salt, baking soda and cream of tartar. Stir into butter mixture with wooden spoon till well mixed.

In the same small bowl combine the 2 tablespoons sugar and the cinnamon.

With adult help, turn the oven to 375 degrees. Grease one or two cookie sheets with some shortening.

Shape dough into 1-inch balls; roll each in the sugar-cinnamon mixture. Put balls two inches apart on greased cookie sheet. With adult help put pan into oven. Bake 8 to 10 minutes. With adult help, remove from oven. Use pancake turner to put cookies on rack. Turn off oven. From the "Better Homes and Gardens New Junior Cookbook"