The next morning, Mrs. Ivanova stood at the chalkboard. "Alex, come show us how aluminum sulfate dissociates in an aqueous solution."

With one click, the answer appeared: a perfectly balanced equation with all the plus and minus signs in the right places. Alex felt an immediate wave of relief. He copied it into his notebook, closed his laptop, and went to sleep, feeling "prepared" for the next day. The Periodic Reality Check

It was Tuesday night, and Alex was staring at Exercise 4 in his Minchenkov Grade 9 textbook . The topic was . The equations for ionic compounds breaking down in water felt like a foreign language. Frustrated, he opened a tab for "GDZ Chemistry 9th Grade Minchenkov."

: He tried the problem himself first, using the textbook's generalization tables . The Comparison : He checked the GDZ only after he finished.