The idea is simple enough: Using a modified rug-beater with criss-crossed strings, hit the small, fuzzy yellow ball over a three-foot net so that it lands within a pattern of squares and rectangles. Simple. Except for the fact tennis balls are known to either go too far or not far enough. This is especially true for newcomers.

That's why tennis programs along the Wasatch Front in recent years have expanded with the growing interest in the game. This summer there will be more classes for a wider range of players. Students of tennis - from those shorter than the net to those older than the telephone - will be able to get a better aim on the game through these programs.Among the agencies offering tennis lessons and leagues are Salt Lake City, Salt Lake County, Sandy, Kearns, Bountiful and Provo. Lessons are intended to be inexpensive, designed for entry-level to advanced players, and for all ages, with about the only requirement being that the player be taller than the racket and able to swing it, not vice versa.

Following is a list of the programs available:

SALT LAKE COUNTY

This is probably the largest of the summer programs. According to Jan Donchess, county sports manager, more than 1,000 people learned better tennis last year through County Rec programs. Among the oldest of programs, Salt Lake County introduced tennis instruction back in the 1940s. The early programs, she noted, were directed at youths. It was about four years ago that the agency started adult programs, she added.

Programs offered include:

Youth Learn to Play, which teaches basic skills for players 6 to 18. Cost is $20 for eight 50-minute classes. There are five sessions, with the first starting June 12.

The Youth Intermediate Learn to Play is for players eight to 18. Cost and dates are the same as the youth program. The youth competitive program is for players proficient in the basics of the game. Teams practice and play once a week, starting in June. Cost is $45 and includes T-shirts, instruction and USTA membership. Also offered are group, semi-private and private lessons for adults and juniors. Costs range from $40 for eight half-hour lessons to $25 for eight one-hour group lessons.

Lessons are taught at 23 different locations in the county. Players may register May 30 from 5 to 8 p.m. and June 3 from 9 a.m. to noon at participating tennis sites in the county, or during the week at Copperview Community Center, Kearns Recreation Center, Redwood Multi-Purpose Center, Magna Recreation Center, Northwest Recreation Center, Cottonwood Heights Recreation Center, and Salt Lake County Recreation offices, 2100 S. State, room 4900.

SALT LAKE CITY

Liberty Park will again be the hub for National Junior Tennis League action. Sponsored by Salt Lake Parks and Recreation and FHP, this is a program that offers junior players lessons, competition and even rackets if they need them. Sessions are held at eight locations around the city.

The program, explained Kathryn Jones, city tennis director, is for kids eight to 18. For $5, and this includes a T-shirt, players meet twice a week for lessons and matches with other young players. Tennis balls will be furnished. The program will finish with a Tennis Carnival on Aug. 7. Jones also said Liberty Park was selected over other western states to hold a NJTL meet Aug. 18-19. The event will bring in teams from other states for a special tournament.

New this year will be a peewee program for players five to seven at Liberty Park and Oak Hills. In this program, players will use smaller rackets (available at playing sites), hit over a shorter net and use a softer, slower tennis ball. Also, there will be Saturday programs offered for the first time at Fairmont and Reservoir parks. Because of increased demand, Oak Hills center on Bonneville Golf Course will be staffed four days a week instead of two. For information on the programs call 596-5036.

Also offered are men's and women's tennis leagues. Women can register Saturday and May 13 and men on May 20 at the park. Leagues will run from early June to August. Players practice once a week and play once a week. Teams are formed on different levels of ability. Fee is $30 per person.

SANDY

Tennis instruction in the Sandy area will involve leagues, youth, novice, intermediate and advanced play. Players will be matched in classes according to their level of ability. Classes will be on Tuesdays and Thursdays. Tennis lessons will be offered at six locations and players will meet Mondays, Wednesdays and Fridays. Cost is $20 for a three-week program. Sessions will begin June 12, July 10 and July 31.

A women's league will run from June 13 to Aug. 11. Cost is $20. Also, there is an adult league for men and women that features competition in singles, doubles and mixeddoubles. Play begins May 26 and cost is $20 for singles, $15 each for doubles. For information call 566-1561, ext. 267.

BOUNTIFUL

Programs in the Bountiful area are geared for adults (16 and over) and youths. There will be two sessions for adults - June 5 and July 3 - that will run for four weeks each, two days a week. One-hour classes for beginners, advanced beginners and intermediates is $20. There will be four youth sessions - June 5, June 19, July 3, July 17. Classes will be one-hour each. Cost is $16.

There is also a junior league program for more on advanced players. This involves instruction and matches. Cost is $40. For information call 298-6120.

OGDEN

Tennis lessons are available for adults and juniors, with morning and evening sessions offered. Adult sessions run from 5:30 to 6:30 p.m. Mondays and Wednesdays beginning June 20. Junior and adult classes will be offered four days a week from 7 to 11 a.m. All lessons will be at Mount Ogden Park. Cost is $15 for juniors, $20 for adults. For information call 629-8253.

For information on Provo programs call 379-6600.

JUNIOR LEAGUE

Junior leagues are run through the different organizations and tennis clubs around the state, such as the Salt Lake City, Salt Lake County and Sandy programs. Players must have a USTA card and, in the case of the three aforementioned programs, the cost of the card is included in the fee.

Play begins June 26. Those registering for the junior league programs will be given times and playing locations. Teams will consist of 10 to 12 players. Matches will be three singles and two doubles.