SAPIX 4th Grade Social Studies Full Set (2018 Edition). I purchased and used this set without any problems (I took the exam in 2022). The following is the product description from when I purchased it: --------- Daily SapiX Each lesson consists of two books: the textbook and the answer key/explanation. All lessons 01-36 are included. These books were actually used by the original owner during class, so there are markings in pen and pencil. Please note that these books have been stored at home and were inspected by a non-professional, so there may be some oversights. ---------