Idaho received a spotty D-plus grade in state rankings released last week by Education Week.

In particular, Idaho was marked down on two perennial trouble areas: K-12 funding and access to preschool and kindergarten. But despite its overall No. 46 ranking, Idaho received some average and above-average scores on several achievement metrics, such as test scores and graduation rates.

Here's a closer look at some of Education Week's Idaho rankings - and some of the related education policy debates that could unfold during the 2015 legislative session, which opens today.

EARLY EDUCATION

Here, Idaho received its lowest grade: an F. Idaho ranked No. 50 among states and the District of Columbia, ahead of only Utah.

With only 32 percent of 3- and 4-year-olds enrolled in preschool in 2013, Idaho ranked No. 50 nationally. With less than 38 percent of students in full-day kindergarten, Idaho again ranked No. 50.

Early education has been a recurring, and emotional, topic at the Statehouse. Supporters tout pre-K as a cost-effective investment in child development. Opponents question whether Idaho can afford to expand its public education portfolio, and suggest young children are best taught at home.

Rep. Hy Kloc, D-Boise, is working on another version of a pre-K pilot bill, which would be largely funded by business partners. In interviews with media Thursday, newly elected state superintendent Sherri Ybarra said she would support this idea.

STATE ACHIEVEMENT INDICATORS

Idaho's C-minus grade mirrored the national average, and Idaho ranked No. 23 nationally.

Idaho's high school graduation rate ranked No. 13 nationally. On test scores, Idaho generally received high marks for closing the achievement gap between wealthier and poorer students.

Idaho's strong high school graduation rate is not new - and in the state's education debate, focus has instead turned to college attendance and college graduation rates. These numbers have long lagged below the national averages. As Education Week noted elsewhere in its analysis, barely 45 percent of young adults attended postsecondary programs in 2013, ranking Idaho No. 47 nationally. Gov. Butch Otter's education reform task force - and its far-ranging list of 20 recommendations - is predicated on getting 60 percent of the state's young adults to receive a postsecondary education by 2020.

The recommendations should loom large in the 2015 session. And the most hotly debated recommendations could be a controversial tiered teacher licensure plan and a related, $175 million career ladder to boost teacher pay.

SCHOOL FINANCE

Another F for Idaho, as it ranks No. 49 nationally.

Idaho's pre-pupil spending ranked near the bottom nationally - even when Education Week weighted the numbers to account for regional cost differences. One telling number: In 2012, only 3.8 percent of Idaho students attended districts that spent above the national average.

School funding issues could pit Republicans against Republicans at the Statehouse.

On Thursday, Otter pledged to present a budget that would restore Idaho education funding to at least 2009 spending levels, although he did not delve into details. But Otter has also signaled he will pursue another round of tax relief in 2015 - and Jeff Siddoway, the influential chairman of the Senate Local Government and Taxation Committee, says he will not consider a tax cut unless he believes education funding has been adequately addressed.