Benjamin, a six-year-old, loves putting together puzzles. He has recently mastered putting together a 10-piece Sesame Street puzzle. His mother claps at his accomplishment but wants to continue challenging Benjamin just beyond his current abilities. The next time they play, she gives Benjamin a 15-piece puzzle and offers some guidance on how to sort the pieces out. According to Vygotsky, Benjamin's mother provides ________ that allows Benjamin's cognitive abilities to be built higher and higher.