I hope you like singing.

Some activities I did and had success with:

Mystery mosaic coloring grids. My kids LOVED them. Obviously you have to help them a lot with the color names, but they did way better than I expected. They couldn't read what their picture was going to be so they were always surprised by whatever they received. haha And the plants vs. zombies ones are hilarious.

https://www.teacherspayteachers.com/Product/MINI-COLORING-BOOK-Pixel-Art-Color-by-Number-1695505

https://www.teacherspayteachers.com/Product/MINI-COLORING-BOOK-Pixel-Art-Color-by-Number-1408165

Also for colors, they enjoyed when I gave them an eye spy sheet and they had to find and color the object and color I call out. "pink.... (they find pink crayon)....... elephant", "blue hat", etc.  Like these:

https://twinkl.co.uk/image/resource_preview_xlarge/AU-A-026-I-Spy-With-My-Little-Eye-Colouring-Activity-Sheet.jpg

 I did some cut and paste activities for seasons (paste the object in the season it belonged and say the season name). I precut them so they would be randomized. They enjoyed that.
http://www.twinkl.co.uk/resource/t-t-18735-seasons-matching-game

Make the alphabet with your bodies.

Head, shoulders, knees and toes song is a great success at that age.

Teach animal names and make or find a worksheet where they can draw the animals and trace the animal vocabulary words. Always have a cheat sheet PPT on the TV so they can look when they have no clue what the word is. Again, always had to be tracing. My "co-teacher" would sometimes wander in to find them quietly tracing and drawing something and look flustered and tell me that they didn't know the alphabet... even though they could identify the letters whenever I taught the alphabet... what....

Simple PPT games were okay, but only for 10 minutes MAX. Sing songs with the vocabulary they are learning. My kids weirdly liked flashcards because if they got one wrong it went back in the pile. They always wanted to be able to pass the whole pile. Made my life easy. haha

It was always hard to fill the 40 minutes.

I feel your pain! I have 2 after school classes a week (one is with 1st graders and the other is with 2nd-4th graders).

A few days a go I bought and downloaded a teaching package from genkienglish.com. It was worth every penny. I have fun energetic curriculum planned for the next two years. It focuses on speaking more than writing, but it comes with coloring handouts and flashcard print outs if you choose to print them. It uses fun songs and games for a 40-45 min lesson. I used it once so far, for the classes I had this week, and I like it. It's saving my sanity lol. It's appropriate for kinder - 5th. My co teacher played "What's you favorite subject?" song in our 5th grade class and the kids kept singing it throughout the day, a great way to remember English. The song made sure to promote the name of the company at the end of the song, that's how I looked up the website.

Here is a 1-12 number trace and color I used for my kindergartners.

Hi,

With the little ones I assume they're learning the ABCs or 3 letter words right?
If you can, it's great to invest in a book like Sounds Great 1 or 2 (it comes with a hybrid CD that has an easy game and story for each unit).

If not, this was my weekly plan:
1. Greet
2. Show them 3 words for each letter (ABC) using the 2-1-0 method
https://www.youtube.com/watch?v=c_N4eRluQVc
3. Then play Missing picture to drill the words
    I do this in a circle on the floor or using magnets to clip the flashcards on the board
    To alternate, you can play a run and grab game by making 2 teams.
    **Repeating the same games is great when you have no co-teacher
4. Do a write out the letters/3-letter-words worksheet

For your next 2 lessons
1. review the words
2. do a write out or match the word/letter to pic worksheet
3. play a pass-the-ball game (always stop before they tire of it though, else you can't use it again soon) or use my matching speed game.
*I've attached an example of the speed game for my Phonics 3 level and flashcards of both books 1 & 2. These documents are free and was downloaded from the publisher's site.

If they're doing ABCs you can let them play in teams or just make a few sets of ABC cards on thicker paper and each lesson add the new letters. They get 1 minute to put it in order. My students used to do it one at a time because the class was small, but individual also works well.
Give them some homework if you want them to remember it better. They can get a sticker if it's done the next week and a sticker for good class participation, to keep behavior in check if you like.

PS Useful songs in addition to class:
1. What's your name?
https://www.youtube.com/watch?v=Uv1JkBL5728
and asked them each time: what's your name?
S: My name is ***. What's your name? (to next student)
until we went around the classroom.
2. Hello how are you?
https://www.youtube.com/watch?v=tVlcKp3bWH8
3. Action song
https://www.youtube.com/watch?v=dUXk8Nc5qQ8
4. Clean up!
https://www.youtube.com/watch?v=SFE0mMWbA-Y
5. Alphablocks jolly phonics (you can play this very often, it will help them learn the phonics quicker)
https://www.youtube.com/watch?v=abaFT722-CQ
*Super Simple Songs will keep you busy with more songs

Hope that helps.
Structure and repetition of activities/games with them is the key.

So I'm adding some ideas I've manged to find and use in class for others who may need some inspiration or ideas.

First of all go to Crayola's website. They have free craft ideas and printables.

One very successful class was making, what they called, Wind Snakes. These were Easy Breeze Spinners. Have them color a piece of paper then cut a spiral. Tape some string to the middle and they can either run with them or hang them in front of a window. It works best with stiffer paper but computer paper is fine.

I also am planning to read a water/ocean related book that I have. Then I am going to give them a "what's in the water?" worksheet. It literally is just a picture of some waves at the top and a line at the bottom. Have them draw whatever was in the book or they know lives in the water.

PS: thanks for all the ideas. And for those asking, my students are literally 1st and 2nd graders. Not 1st or 2nd years. These are elementary school kids.

PPS: I'll probably add more at a later date.