Okay so it's been 4 months now, and I'm almost completely out of how to entertain elementary grade 1 and 2 for 90 minutes.
I have 1 class that is 40 minutes which is absolutely fine, enough to do some kind of activity or craft, but my other class is 90 minutes long and its driving me crazy. I've done colouring, which they're now sick of, we're still focusing on the alphabet but doing more than 2 or 3 new letters a week is pointless. I don't wanna become one of those teachers who just sticks cartoons on for the whole 90 minutes, but I don't know how else I can entertain them for this long, even I'm bored!
I thought maybe splitting the class so 30 mins work, 30 mins cartoon, 30 mins work, but getting them to sit back down after watching a cartoon is impossible.
Any advice at all would be great.....

Okay, for grades 1 and 2, I go to youtube for lesson ideas. I usually pick a song that goes over something in, like fruit or what ever. {I'll leave links of a few videos I have used at then end.} Then I build a whole lesson around it.

 Going with the example, fruits, I would watch the video, make a powerpoint going over the video terms. So in this case, all the fruit and the key expression, "I like....or I don't like." Then I would play the song twice, first time watching, second time singing, and a  third time if they are having trouble speaking or singing any of the parts.

Then I usually do a listening, game. Like bingo, twister (you cut out the picture of the items and tape them to the floor. Have one kid placing arms and feet down while everyone else shout out the terms.)

Then I would do a brief test your knowledge game on the powerpoint, like have four pictures of fruit up and have the kids point out the correct one you are saying. I also use a ball during this. So I have students toss it around to each other as a way to pick who is going next.

Any writing activity I have them do as the last part of class. I never just give a coloring sheet. I only give out coloring sheets, if they completed the writing/tracing assignment. I keep the coloring sheet in with the theme of the lesson. So a fruit bowl coloring sheet for this lesson. I also play music as they work, something relaxing. The next lesson, I would open with a review game with fruit. And if they are still having trouble with the subject matter....more games with the fruit theme until they got it down.

Link time:

https://www.youtube.com/c/thesingingwalrus/videos

https://www.youtube.com/channel/UCJJmDk_lxosfvRFiwgOn6xw

https://www.youtube.com/channel/UCpnqph0QcA4FMHGdyGDFaZA

https://www.youtube.com/channel/UC8NFs-VWUsyuq4zaYVVMgCQ

https://www.youtube.com/channel/UC4Hdb26_xnPQsntwLazMqYw

If you are still struggling, take a look at a 3rd Grade book. See what things, they will need to know and you can build your lessons around that.

Music to knock out your students:

https://www.youtube.com/watch?v=l1Q-cI4RE5s

Good Luck!

Ouch, it's already difficult dealing with my 40min class with my 1-2 graders (elementary). 

Crafts are definitely the way to go.  For example, we learned about family words (mom, dad, family, brother).  Then I made them create their family using those bendable pipe cleaners.

Don't restrict yourself to conventional learning when it comes to the 1-2 afterschool class.  You'll run of out ideas quickly.  I even did some physical English.  Learn about the body parts, then attempt to do kids yoga and exercises. 

You can also do some basic science.  We played with balloons and static electricity. 

Sure phonics are great, but realistically, if you have 30 1-2 graders and no Korean teacher to help with you, they will get bored quickly since most things you say will go in one ear and come out the other.  Games, activities, crafts, and SONGS all work great.

 If you're reallllyy tired, find a movie.  My students can actually keep up when it comes to reading the Korean subtitles fast enough. I usually teach the some vocab before the movie.  They usually yell out the words in English when they see it on screen.  We all have those days where we just want to pop in a movie, don't feel guilty about it, haha.

Its amazing how different the 2nd graders are compared to 3rd graders.  1 year sure makes a difference.  My 2nd graders last year were wild, found phonics boring, and only wanted to learn vocab and phrases.  Suddenly, when they moved on to 3rd grade, they join my my 3-4 grade afterschool class, now they try to read everything in English now.  They're also really interested in English during regular classes.

I really don't see them making changes... Try You tube videos, coloring pages, abc you tubes and Barry's fun English is an awesome help... I am jacque52... I input my own things. Barry's Fun English is the way to survive.
1st and 2nd graders really like the card match and and the bomb game. 

I know it is rough... I am in the same boat.