All of the sensorial materials were designed to isolate the one quality that is to be worked with by the child. Such emphasis on the particular sense fosters its refinement, allowing the child to center all the attention on that one quality fully without being distracted by other senses. Today, we are focusing on the visual sense while training memory.
Choose any set of three to five objects (or more depending on your child's age), and invite your child to remember the content. Then, periodically, while covering all the objects in a set with a napkin or a rag, inconspicuously remove any one object and ask your child if s/he can remember which particular object is missing.
https://player.vimeo.com/video/229566420 You would play this memory game with one set of objects at a time.
This game is a great cognitive reinforcing activity, and you can incorporate it while learning new subject (like a new group of animals) or you can use familiar household objects like a favorite toy, a tool, a fork, or a food and play in a similar manner.