Try to solve the exercises on your own before looking up the answers. It's the best way to actually remember the rules.
It looks like you're searching for study aids or "GDZ" (готовые домашние задания) for the textbook by L.Y. Zheltovskaya and O.B. Kalinina . spishi.ru russkii iazyk 3 klass zheltovskaia
Developing "orthographic vigilance" (spotting tricky spelling spots). Try to solve the exercises on your own
Parts of speech (Nouns, Adjectives, Verbs) and their basic inflections. spishi.ru russkii iazyk 3 klass zheltovskaia
If you’re checking a parsing exercise (like phonetic analysis or sentence structure), make sure you understand why a letter is silent or why a comma is there.
Make sure the answers you find match the year of your textbook, as exercise numbers sometimes change in newer editions. Common topics covered in this level: Root word changes and prefixes.