As California works to overhaul public education, federal funding could be in short supply.

The U.S. Department of Education isn't thrilled with California's new tests.

The state is in the middle of switching to Common Core and what's called a "Smarter Balanced" test.

They're supposed to make curriculum more applicable to working conditions.

According to the Mercury News, California schools are dumping the STAR tests for Math and English, which are preferred by federal school officials.

Now a harshly worded letter is coming from the U.S. Department of Education, warning California that students need to take the standardized math and english tests, and if they don't, they stand to lose about $3.5 billion in funding.

Local districts are banding together to write a letter in response, noting that the federal government has never taken away money from a state's education budget this way before, and they don't expect that they'll start now.