GREENWOOD, Ind. (AP) — A decision by Indiana lawmakers to postpone full implementation of new school standards has left teachers uncertain whether new lesson plans they’ve worked on for two years can be used.

The Common Core standards were developed by a national group of school officials and have been adopted by 45 states. They emphasize analytical reading and writing skills in all subjects.

Indiana adopted the standards in 2010 and uses them in kindergarten and first grade. The state planned to expand them to all grades starting in the 2014-15 school year.

Lawmakers ordered a delay to study the costs of implementing or abandoning the standards.

School officials tell the Daily Journal that switching the standards could confuse younger students and make it harder to find current teaching materials.