Finding a reliable (answer key) for the 1st-grade mathematics curriculum by Arginskaya, Benenson, Itina, and Kormishina can be a lifesaver for parents navigating the "Zankov system."
Since 1st-grade math is highly visual, these guides usually include scans of the drawings and diagrams required in the workbooks. Cons:
You can easily find these for free on popular Russian educational portals like Gdz.ru , Pomogalka , or MegaResheba .