The Indiana legislature is moving fast to cut at least three hours from the state ISTEP after two weeks of sharp words and behind-the-scenes negotiations over its length. Lawmakers are expected to rush a bill through both houses for the governor to sign next week to make the changes.

But with kids just days away from taking the exam, some are still asking: what caused the blow up?

The answer is a little complicated, but here are six reasons why ISTEP more than doubled in length from last year:

1. When standards change, tests must also change.

A big fight over Indiana’s academic standards last year ended when the state rapidly changed course and adopted quickly assembled new standards.

That disrupted a carefully coordinated plan in place since 2010 for the Indiana to adopt Common Core Standards along with 45 other states and use a shared exam that would test student knowledge with results that would be comparable across the country.

When Gov. Mike Pence and state Superintendent Glenda Ritz took office in 2012, Indiana had already adopted Common Core. Schools were putting it in place grade by grade, and a new Common Core-linked exam was scheduled to replace ISTEP this year.

But Pence was wary of the shared test — called the Partnership for the Assessment of Readiness for College and Careers or PARCC — and ordered the state to withdraw from the consortium creating the test in 2013. Six months later, both Pence and Ritz supported the idea of Indiana dropping out of Common Core and endorsed new locally made standards that were adopted last April.

Like Common Core,  Indiana’s new academic standards are more in-depth and ask students to do more analysis and critical thinking.

A test matching those expectations was needed in a hurry. Instead of taking years to adapt to the new standards and create the new exam, Indiana tried to do the whole process in a matter of months. That meant asking a lot of the 2015 ISTEP.

2. This year’s test had two extra goals — add questions to match the new standards and help create a test to replace ISTEP in 2016.

More difficult standards naturally meant Indiana needed a more difficult test. But there wasn’t time to completely overhaul ISTEP this year.

Instead, ISTEP was modified for this year to add several extra features. Many of the new standards were similar to the old standards, so many questions roughly matched the style and difficulty of past ISTEP exams. But new questions were added to also test students on new, tougher concepts included in the new standards, which were designed to make sure they graduate high school ready for college and careers.

The online version of ISTEP, for example, includes more advanced testing methods that ask kids to not only answer multiple-choice questions, but also answer questions in new ways, such as by dragging and dropping points on a graph or using drop-down menus.

Finally, this year’s ISTEP had one more job: Try out some questions that could be used on the 2016 exam.

But there was a problem. Indiana law requires release each year of all essay or short-answer test questions that are used in scoring. This would turn out to be a big factor in the length of the test.

3. A huge number of questions on this year’s test actually don’t count in a student’s score.

When test questions are released to the public they are effectively retired. They can never be used again on ISTEP.

So for this year’s exam, there were two big sets of essay and short answer questions: one group that counted toward each student’s score and must be released plus a large second set being tried out for use in 2016 that wouldn’t count.

Trying out questions is important. Test makers examine how students score on them to look for unexpected surprises. Questions they ask include: Was the question harder or easier for students than predicted? Was there reason to believe it was confusing to children? Was there any evidence the question was unfair to certain groups of students?

Trying out enough questions to be able to make a completely new test for 2016 was the main factor that caused what is normally a six-hour test to swell to more than 12 hours this year. All along, however, this was intended as a one-year problem. Future state exams are expected to be only slightly longer than the six-hour tests of the past.

The legislature appears poised to waive for one year the requirement that all essay and short-answer questions be released. This would allow some of this year’s questions to be reused so there could be far fewer extra questions that don’t count.

4. A longer test means more school days devoted to testing.

Indiana students don’t take all of ISTEP at once. They take sections of the exam in smaller doses over several days.

At its Feb. 4 meeting, the state board increased the number of days schools are allowed to use to give the test. The tests will be given over the course of almost a month, beginning Feb. 25 and ending in late March, followed by another set of testing days over three weeks at the end of April into May.

Schools can choose how to split up the parts of the test. Students might take just one section per day or do more depending on what teachers and principals decide. Danielle Shockey, the state’s deputy superintendent, said a testing day could take many shapes. In some schools, student take one 35-minute test section each day. In some schools, they spend an hour each day on testing. Other schools may do more.

“They have a long window of time,” Shockey said. “They can take one session a day if they so choose. It’s a local choice.”

5. Test makers had to consider that ISTEP is plays a critical role in school A-to-F grades and teacher evaluation ratings.

ISTEP is used to measure two things: how much students know of the content they were expected to learn this year, and how much they’ve improved from a previous year. Both factor into how Indiana measures the quality of schools with its A-to-F grading system, as well as how it evaluates teachers.

To determine a school’s A-to-F grade, the state considers both the percentage of students who pass ISTEP and how much students improved from last year. For teachers, the state expects to see their students’ test scores improve over the prior year.

When tests are roughly the same each year — measuring the same standards and using similar types of questions — it is easier to gauge how much students improved from the prior year. But when the standards change and the questions are crafted differently, test makers have to add extra questions to help determine each student’s improvement from the last test.

This spring’s test will include a few questions in English and math that are specifically designed to estimate roughly on what grade level each student best fits. For example, a fourth grade test might include a few third grade level questions and a few fifth grade level questions. Some students might do well on only the third grade questions but poorly on harder questions. Others might do well on all the questions, even the more challenging fifth grade questions.

Those extra questions help the test makers better estimate whether the student improved a little, a lot or not at all over the prior year. However, those extra questions also lengthen the test, but only by minutes, not hours, Michele Walker, testing director for the education department, said. The legislature agreed they were worth keeping — those questions will remain under the plan to shorten ISTEP.

6. Then, there’s the social studies question.

The federal No Child Left Behind Act, signed into law by President Bush in 2002, requires states to test students in English and math each year in grades 3 to 8, and once in high school, and also in science once during elementary, middle and high school.

Noticeably absent? Social studies.

Although Indiana’s social studies ISTEP test is only given to fifth- and seventh-graders each year, accounting for about an hour of testing for those grades, Pence’s test consultants recommended cutting that subject to reduce testing time further since it is only required by state law. That means the legislature could make an exception for this year.

State board members were divided on this idea. Some worried that it would send the message that social studies is not important. Others argued one hour for just two grades doesn’t add much test taking time.

But the legislature liked the idea of reducing test time further this way, so the Indiana Department of Education has told schools to expect the social studies exam to be optional this year. That means some students will take it, if the school decides they should, and others will be allowed to drop it for this year only.