Misconception: Students think you can use the “item (any) of (list)” block in Snap! and Scratch to check for every item in a list, but this block actually returns a random item.
Misconception: Students incorrectly believe that variables passed into a block in Snap! will get modified; however, a copy of the passed-in variable is what the block receives and modifies.
Mention to students that individual blocks in Scratch and Snap can be tested by double clicking them in the block library so they know this useful, non-intuitive trick for learning what an individual block does.