Hello!
For 3rd and 4th I usually pick a topic and stick to that for the entire month since I would only see them once a week.
Topic examples include colors, food, animals, numbers, action words, etc. Similar to what's in the Grade 3 curriculum. My structure for a class is typically an ABC song to start (I do the Super Simple Songs ABC Chant), phonics (I use a synthetic phonics curriculum i.e Jolly Phonics), a PPT lesson with the vocabulary words, I play a song using the words we learn, then we play a game. I'll usually play stuff similar to what I do in curriculum classes or google search my topic + ESL games to get some ideas. Sometimes instead of a game we will do a craft or project.
You can also just review and expand upon the lessons they learn in their classes.
With Grade 5 and 6, I do a lot of project-based learning and will play card and board games with them. What you can do depends on how many are in the class. I try to get them to talk as much as possible and I like to focus on conversational stuff like my name is, I'm from Korea, I like video games and chicken, I'm ____ years old, etc etc. I had them make a book once where each page was a sentence. Sometimes if there is a holiday or I feel like teaching them about something cultural we will do a lesson around that.