Johnny is currently struggling with math problems that require him to "carry" the tens place to the next column. even with an expert instructor, johnny is not ready to learn algebra. learning algebra would be in the limit of the zone of proximal development for johnny.

upper

Explanation:

Zone of Proximal Development or ZPD is a concept developed by Vygotsky. It means the distance between what a person can do alone and what he can do with the help of or guidance from a skilled person.  

ZPD has two limits. A lower limit, which is the things that are difficult but possible for a person to learn alone, and an upper limit i.e. the things that a person cannot learn, even with assistance from an adult.

Here, Johnny cannot learn algebra even with an expert, so learning algebra is in the upper limit.

omg stop xd you need to chi