Alphabet is a good start for 3rd & 4th. I used some flash cards I found in my classroom. they were from the text books a few years back so they sort of matched the current lessons. I would look through them and use the ones for what we were learning now. I just had them repeat the words broken down until they could repeat it back. it was boring and hard for them, but they did improve. i suppose you could even use PPT'sI also used writing sheets for the alphabet, just one or two letters per class. but they would write them like 20 times, Aa Bb Cc. i would focus on numbers too, connect the dots and then they can color the picture.Once they showed improvement I went on to have them write the vocab words from class. we even got up to reading Clifford books! at first i would read the sentence and they would repeat it. eventually one student was able to read on her own .and my tutoring classes were 40 minutes which is a long time for a kid. so after 20-30 minutes we would play a game together. or they could color or something. maybe for the 6th grader you could make some word searches for the current lesson. there's a few site that let you create them. or give him a writing worksheet. idk, i have one student who doesn't participate either or when he speaks he uses a silly fake voice.