Yay Minnesota! Home of 3M & Medtronic (among many others), we certainly have plenty of reason to emphasize STEM.
It's noted in the article that the Minnesota science assessments (MCA-II) are completely computer-based (something that the testing industry has long avoided). The test uses innovative item types to get at students' scientific reasoning and inquiry skills.
The draft test specs for the next version of the science assessment, MCA-III, have been recently released for public review, and I'm looking forward to looking at them.
Full Disclosure: My dad is a psychometrician at Pearson, who analyzes the results of the MN science assessment. He may have juked the scores to make me feel better...