High school graduates with weak academic records often have to take remedial college courses when they start college to help them catch up to the rest of their classmates. But even high-achieving high schoolers may score poorly on college placement exams - and end up in remediation to bring their skills up to par.

One in four college students ends up in remedial classes in college because their reading, writing or math skills are discovered to be below an acceptable level, according to a 2016 report from Education Reform Now. That could be because those students took time off before college and their skills got rusty. It could be because their education got disrupted by illness or other special circumstances.

Or it could be due to the structure of their high school curriculum itself. Students in Iowa, for example, only need three years of math to graduate high school. That math-free senior year can play havoc with students' numeracy skills. At Eastern Iowa Community Colleges in 2014, 69 percent of students coming from an Iowa high school had to take a remedial math course.

Remedial courses can bring you up to speed, but they cost money and don't count toward your degree. That means you have to spend money on extra courses (nationally, college freshmen borrow an extra $380 million a year playing catch up in remedial courses, says Education Reform Now) and wait even longer to graduate.

So how can you avoid such a fate?

Here are a few tips from Mark Boggie, the assistant dean of student services at Cochise College in Arizona:

- Take challenging classes in high school. Push yourself to do what's difficult. Take AP or dual credit courses. It's important to stretch your mind and expand your skills.

"Although this does not guarantee the students' success in postsecondary courses, it better prepares students in having the skills and knowledge needed to be successful," says Boggie.

- Don't give in to senioritis. It can be tempting to coast through your senior year, especially if you've already completed your math requirements, for example. But you need to keep your knowledge - and your grades - up.

"It has become common for students to take an 'easy schedule' during their last year in high school," says Boggie. "This practice promotes degrading of knowledge and skills needed to be successful in the college environment, making it more likely that students will waste time and money in remedial coursework."

- Prepare for placement exams. You know they're coming, so be ready. Review your coursework and hire a tutor if you need extra help. See if practice tests are available.

"Some institutions base placement on a single test score (either a placement exam or a national test like ACT or SAT); others have more holistic methods to place students while taking into consideration students' coursework in high school, level of rigor, GPA, etc." says Boggie. "Once the student knows the method of placement they should practice and prepare to take any placement test that is necessary."