Cognitive games (1951)

Can you solve the cunning problem of an ancient Arab mathematician? Can you blow a huge soap bubble? Do you know how to create smoke without fire? Do you decipher mystical letters? Determine which river flows in the mouth?
The game is one of the best ways to fix the knowledge gained and at the same time spend a good time with family or friends. This book contains dozens of entertaining and cognitive tasks. All of them are divided by topics: mathematics, physics, chemistry, literature and geography. Explanatory illustrations and schemes have been prepared for each riddle and rebus, and crosswords and some other tasks can be solved immediately in the book. At the end, answers to all tasks are published, as well as detailed comments.
The book will appeal to children and entertain their parents, and will also be useful to teachers during school or extracurricular activities