The marble is buggy, often not moving when you try to drag it. Very frustrating. The math required is beyond the average 5-year-old, and the option to roll the marble takes more patience, finesse, and coordination than most kids have at that age. On some tasks, it involves Roman numerals -- when are kids taught those? The instructions say you can customize the level of difficulty and skills, but there is no access anywhere to the little "wrench" icon one is supposed to click to customize! Very frustrating and disappointing. My daughter tried it twice for about 10 minutes and gave up. I wish there was a way to sample these apps before buying.