You can find and download these materials (often in PDF or Word format) through several educational resource portals. Here are the most reliable types of sites to check:
Поурочные разработки по русскому языку: 3 класс (Lesson developments for the Russian language: Grade 3).
Методическое пособие к учебнику Т.Г. Рамзаевой (Methodological guide for T.G. Ramzaeva's textbook).
Often hosts direct links for teacher guides and lesson planning books.