This is the official government textbook. Press Open link, choose Class 4 and then Bangladesh & Global Studies on the NCTB website.
About this textbook
"Class 4 Bangladesh & Global Studies (Textbook)" is a textbook for Class 4 (Bangladesh & Global Studies). Edition: Official NCTB textbook. It is part of Holy Cross Learn, the free online learning platform of Holy Cross Rajshahi. No login is needed and it works on phones.