A summer nature walk on the beach

''Yuck!'' might have been a typical parental reaction.

But instead of registering either surprise or disgust at the lifeless jellyfish the youngster was holding up for approval, Janice Albright responded with a hearty ''Good find!''

Ms. Albright, director of education for a bird observatory in nearby Manomet, was leading a group of five children and three parents on an afternoon beach walk along the historic waterfront here. As each youngster came up to her with a sandy handful of discovery, she took time to answer their questions and ask more of her own.

''Are horseshoe crabs real crabs, do you think? Turn it over and see what it reminds you of. A spider? Right! They're ancient cousins of spiders, from the time of the dinosaurs. And what about that tail? Do you think it can sting? Nope! The horseshoe crab just uses its tail to flip itself back on its feet if it gets knocked over by a wave.''

As their children's enthusiasm caught on, the parents began bringing bits of shells, crab legs, and seaweed to Ms. Albright, too.

''Those things that look like roots?'' she asked a mother holding up a long, stringy piece of kelp. ''They're 'holdfasts.' That's what the plant uses to attach itself to rocks in the ocean.''

Ms. Albright, a former teacher of ''Sharing Nature With Your Children'' at the University of Rhode Island, says many parents are reluctant to take their youngsters on beach or forest walks for fear they won't be able to answer questions. ''They are almost afraid of the fact that they don't have a great knowledge of facts,'' she notes. ''They say, 'How can I teach my child?'

''What I tell them is that all they have to do is give their children a sense of wonder and share their enthusiasm and look for things together. That's the best way to approach it.''

On the beach walks she leads, Ms. Albright often passes out index cards with handwritten clues that can lead to unusual treasures:

* Find an animal that matches the color of the sand.

* Find a plant that attaches itself to something else.

* Find an animal that attaches itself to something else.

* Find an animal that hasn't grown up yet.

* Find a plant that has something to help it float.

* Find something people have left behind.

Her one restriction on collecting is an admonition to pick up only dead specimens.

Some of the best introductory books for parents and children, Ms. Albright says, are the inexpensive ''Golden Guide'' series available in most bookstores and supermarkets. ''They have a wealth of information and are written for people who are just beginning to discover what's out there.''

At the Cape Cod Museum of Natural History, Donald Schall has a few more pointers for the parents who come to him with questions about taking their children on adventures outdoors. ''I tell them they don't have to have all the answers, that they're only guides,'' he says. ''If they and their children find something on the beach that's abundant, picking up one specimen isn't going to damage the local population. They can take it to a museum or natural science center, where the staff will be only too happy to help identify it.''