My eldest daughter used these, but she no longer needs them, so I'm selling them. They were purchased from Zenkaken. They have been used, so there are scratches, stains, bends, and writing. Please understand this. (See images 1-17) 1. FRESTA Science, Grade 2, Problem Edition 2. FRESTA Science, Grade 2, Summary Edition & Explanation/Answer Key A set of 2 books. The Problem Edition has 104 unused pages. The Summary Edition & Explanation/Answer Key has no writing. Would these be useful for any children?