Teacher-librarian Val Ehlers spots a student holding a thick chapter book. She knows his reading level and what he's been working on in class, so she intervenes.

"Is that a right-fit book for you?" Ehlers asks the Marshalltown student. It's not, so he returns to the shelves to find a new one.

It's an important interaction, but it's becoming increasingly rare.

Iowa students are less likely to come in contact with a school librarian now than a decade ago.

For every five school librarians working in Iowa 10 years ago, only four positions remain, a decline of nearly 20 percent, the Register found. Comparatively, the number of teachers has grown 8 percent in that time.

In the last two decades, the decrease is even sharper. The number of Iowa school librarians dropped 40 percent, from about 700 to roughly 400 positions, in that time, according to the Iowa Department of Education.

In Des Moines Public Schools, the largest district in the state, serving 32,000 students, there is one teacher-librarian on staff.

The reduction in teacher-librarian positions has implications for students, according to advocates.

Librarians are certified teachers who can determine whether students are prepared for college assignments and whether they know how to research issues online and in text.

Instead many schools are hiring associates to run library programs — they cannot teach, and do not have a masters of library science degree, which is required for teacher-librarians.

"You wouldn't want to replace any other certified staff member with someone who's not certified," said Valerie Ehlers, president of the Iowa Association of School Librarians. "You don't do it to science, you don't do it in English, to art, music, P.E. Why would you want to do it to a teacher-librarian?"

School librarians by the numbers

Across Iowa there are about 400 teacher-librarians for 485,000 students in Iowa's public schools. Twenty years ago there were about 700 teacher-librarians for 482,000 students.

Twenty years ago, there was one librarian for every 700 students.

Now, there's an average of one librarian for every 1,200 students.

Des Moines-area teacher-librarian positions:

Ankeny: One per 1,800 students

Des Moines: One per 32,000 students

Johnston: One per 1,000 students

Urbandale: One per 1,000 students

Southeast Polk: One per 1,700 students

West Des Moines: One per 800 students

Waukee: One per 900 students

Sources: Statewide enrollment and librarian figures are from 1997-98 and 2016-17; district-level enrollment is from 2017-18, all from the Iowa Department of Education. District-level librarian figures are from a recent Register survey. Numbers have been rounded.

To view the chart on all platforms, click here.

Librarians are 'spread so thin'

Teacher-librarian Kathy Houck splits her time between four districts in northwest Iowa.

On Monday mornings, she'll model a lesson for a retired teacher-turned-associate, who'll re-teach it to elementary children in Webster City. Other associates she works with don't have that background, so they'll read classes a story instead.

On Tuesdays, she's in South Hamilton, spending mornings at an elementary school and afternoons at the junior-senior high. The latter doesn't have a staffed library, so she's trained student assistants to help classmates find and check out books.

And once a month on Wednesdays, Houck spends a half-day in Stratford's K-6 school, where books are mostly checked out on the honor system.

Combined, she's there four days each year.

"I see classes for half an hour once a month," she said. Unless teachers are practicing what she teaches in the classroom, "the kids listen .. and they walk out the door and they forget it."

"There would be more integration (with classroom lessons) if I wasn't spread so thin," Houck said.

Librarians say libraries are the heart of a school — supporting all the learning around it. Librarians assist classroom teachers, instruct students and run library programs.

"We don't want to cut back to multiple buildings or para-lead libraries," said Kay Ingham, director of curriculum and special services in Bettendorf, which still has a librarian in every school. "We think we lose a lot in that."

Less time spent with students

Teacher-librarians in Iowa's public high schools spend less time directly interacting with teachers and students, which used to take up the bulk of their week.

Time spent collaborating with classroom teachers, averaged per 1,000 students.

In 2009: 15 hours a week

In 2015: Five hours a week

Time spent instructing students on information literacy, averaged per 1,000 students.

In 2009: 26 hours a week

In 2015: Eight hours a week

Source: "Mapping the State of Iowa School Libraries," by Ericka A. Raber and Rob Shepard, October 2017, Iowa Library Association.

Librarians linked to reading scores, college readiness

Retired professor Jean Donham saw college freshmen lack even basic skills in discerning information during his years in the classroom. They'd cite a popular magazine instead of scholarly articles.

"I'd have kids come to the library who had no clue how to begin to dig into scholarly resources and what kind of information their college professors were expecting them to cite," said Donham.

School librarians can help students prepare for the kind of research needed in college. And more than 60 studies show that a quality library program improves student reading scores, said Ehlers, who's president of the Iowa Association of School Librarians.

That's noteworthy, given the declining math and reading scores on Iowa's accountability exams for the 2015-16 and 2016-17 school years.

Low-income and rural communities have been hit harder than others. There's an inequity in the staffing of Iowa school libraries that can further the gap between low-income students and their wealthier peers.

"We have districts where we have amazing libraries, well-staffed, well-resourced," Donham said. "Then we have libraries where they come in maybe once a month, maybe on call."

Libraries and reading scores

Research indicates that a strong school library program can increase reading scores and help children from disadvantaged areas.

Large-scale studies of more than 2.6 million students found that a of more than 2.6 million students found that a strong library media program increase d reading scores by an average of 10 to 20 percentage points.

Schools with a full-time librarian have student achievement have student achievement up to 35 percentage points higher than those without a librarian, according to a Michigan study.

Access to books can help on reading achievement. That's key because two out of every five Iowa school children now come from a disadvantaged background, state data show. offset the impact of growing up in poverty on reading achievement. That's key because two out of every five Iowa school children now come from a disadvantaged background, state data show.

Source: American Association of School Librarians.

To view the map on all platforms click here.

Are librarians being replaced?

Ankeny schools created a district-level teacher librarian who oversees its 10 elementary schools this year, and changed what was previously librarian positions to teacher positions.

Elementary school librarians are essentially being phased out; a master's degree in library science won't be required for new hires. "School districts need to do what we need to do," said Corissa Thompson, the district-level K-5 librarian. "It's hard."

A former classroom teacher, Thompson didn't know what free resources she could access until she began to work with a school librarian. Doing so improved her teaching and her students' learning, she said.

"Teachers who have never had access to a quality librarian have no idea what they are missing," she said.

Teachers can instruct students, but librarians offer specialized knowledge that will likely be lost with the change. "We dig much deeper in many areas, and then we collaborate and support both teachers and students," she said.

Other schools are seeing similar changes. Des Moines Public Schools has one teacher-librarian position. Associates, who cannot legally teach, staff more than 60 schools.

"State funding and budgets have consequences, and this is one of them," Des Moines spokesman Phil Rhoeder said.

There are no set hours for Nevada school's teacher-librarian, who is contracted from another district. Legally it's a 0.1 position, but practically the librarian serves as needed, said Superintendent Steve Gray.

Instead, associates run the library, including circulation, supervision, ordering and organizing.

All those scenarios are acceptable under state law, which only requires that districts employ one teacher-librarian, but does not specify what that means.

Aware of the concerns, the Iowa Department of Education organized a teacher-librarian group to recommend best practices as part of meeting the federal Every Student Succeeds Act, which replaced No Child Left Behind.

The group's findings may be released as early as January, said Amy Williamson, school improvement bureau chief for the Iowa Department of Education.

"The real question is: Is what you're doing feasible, reasonable, and is it in a way the will get the best results for the program?" she said.

Ericka Raber, who’s studied changes in school library programs through the Iowa Library Association’s college readiness committee, said it's crucial that students learn the skills librarians have traditionally taught.

It's researching a college paper, but it's also knowing how to access and understand credible information they'll use to buy a car, launch a business or engage in political debates.

"They will have to make informed decisions based on the information they receive," she said.