The high school class of 2006 posted the biggest score increase on the ACT college entrance exam in 20 years, and recorded the highest scores of any class since 1991.

Utah students followed the national trend of scoring the highest since 1991, with an average score of 21.7, higher than the national average of 21.1. ACT scores range from 1 to 36.

The average composite scores on the exam, which measures students' readiness for college-level work, rose to 21.1 from 20.9 last year. Utah's score rose from 20.9 in 2005.

"This is good news," said Utah State Superintendent of Public Instruction Patti Harrington. "More of our high school students are thinking about going to college since they're taking the test; more of our high school students who plan to go to college are taking the rigorous courses they need to succeed; and more of our students are performing well on these national academic tests."

Both boys and girls posted gains, as did all racial groups except Hispanics, whose scores held steady. Officials at the independent, nonprofit ACT said an increase of 0.2 points is significant when considered across a record 1.2 million test-takers nationwide, or 40 percent of graduating seniors.

"It takes an enormous amount of change for that large a group to move even a little bit, particularly when that group is changing and we're seeing more students take the ACT for the first time," said Richard Ferguson, CEO of the Iowa City, Iowa-based organization.

Utah saw a 5 percent increase of students taking the test this year, representing 69 percent of the 2006 graduating class or 21,561 students.

Some of the improvement may come from the ACT's growing popularity among high-achieving students in states where the rival SAT exam has traditionally been more popular. The ACT is more attractive to some students because it focuses more on material covered in high school classes than on general ability.

In Connecticut, 12 percent of 2006 graduates took the ACT, up from 10 percent a year ago, and scores rose from 22.8 to 23.1. In New Jersey, 8 percent took the test, up from 6 percent of 2005 graduates, and scores rose from 21.3 to 21.8.

But Ferguson said the national increases were broad-based. Illinois and Colorado -- the two states where nearly all 11th graders are required to take the test -- saw scores rise 0.2 and 0.1, respectively. Other states with large numbers of ACT takers, such as Kentucky and Tennessee, also recorded increases in line with the national gains.

Historically, the ACT has been more popular in states in the center of the country, while the SAT predominates on the East and West Coasts. But in addition to Connecticut and New Jersey, Florida, Delaware, Vermont and New Hampshire all had double-digit percentage increases in the number of students taking the ACT.

Next year, Michigan will join Illinois and Colorado in administering the test statewide to 11th graders, and Kentucky will follow in 2008.

ACT officials said the numbers are encouraging but still show too few students are prepared for college-level work. Only 21 percent of test-takers scored the benchmark indicating they are likely to succeed in college on each of the four exams -- math, English, reading and science. More than two-thirds hit the benchmark score in English, but barely one-quarter did in science.

"This doesn't mean they won't be successful and graduate from college, but it does increase the likelihood they will struggle or need remediation along the way," Ferguson said.

Utah's average reading score of 21.4 is just over the benchmark of 21. All of Utah's other scores, however are just under that point. In math and science, the majority fell short of the benchmarks. Utah scored 20.8 in math, where the benchmark is 22, and 20.9 in science, where the benchmark is set at 24.

Students persuaded to take a full core curriculum -- including four years of English and three years each of math, science and social studies -- do better on the ACT and are more likely to succeed in college. In Utah, the 49 percent of students who reported taking a full core scored an average of 22.6. Twelve percent of Utah students didn't report their core class information.

The percentage who reported taking the core -- which is more than many states require to graduate -- actually fell from 56 percent to 54 percent this year.

"The message still isn't getting across to far too many students," Ferguson said.

In Utah, the 39 percent of students who reported taking less than the full core curriculum scored an average of 20.7.

Earlier this month, the Utah State Board of Education voted unanimously to raise high school graduation standards from three years of language arts and two years each of math and science to four years of language arts and three years each of math and science. The change will take effect for the class of 2011 -- this year's eighth graders.

Nationally and in Utah, educators were encouraged by the increases in scores from minorities.

Average scores for black students rose 0.1 points to 17.1, while Hispanics' scores were steady at 18.6. Significant racial gaps persist: Whites scored 22.0 on average and Asian-Americans 22.3. Even black students who took the core were outscored by white students who had not -- which Ferguson attributed to a range of factors, including insufficient rigor in the core courses offered to minority students.

In Utah, black students scored 18.2 in 2006. There were 148 black students in Utah who took the test. Hispanic students scored an average of 19.3, with 801 students taking the test. Asian American and Pacific Islanders, who made up 4 percent of Utah test-takers, scored 20.7.

The average score for boys rose 0.1 percent to 21.2, while girls' scores rose 0.1 to 21.0.

The ACT also released the first results from a new optional essay section, launched in February 2005. About 36 percent of test-takers completed the essay portion and they scored on average 7.2 on a scale of 2 to 12. Girls outscored boys by half a point.

Utah students' average score in the writing section was 7.7. However, only 17 percent of those taking the test as 2006 grads opted to take the writing test.

SAT results for the class of 2006 will be released later this month. Most colleges accept either the SAT or ACT when considering an application.

This story appeared in The Daily Herald on page A1.