Crows are great problem solvers. They’ve been seen to leave nuts in the middle of the road so when cars roll over them the shells crack. The crow can then swoop down for its food. Multiple studies have also been done with crows and birds in the same family (Corvids).
A few experiments have been done where crows would have to raise the water level in a tube in order to get to a floating treat. They could distinguish between pebbles that would displace the water and useless pieces of cork that would just float. The same experiment was done on children and shows a crow has the same problem-solving abilities as an eight-year-old.