Mixed Media or watercolor or Acrylic paper 9 x 12 ( inch).  Please make sure the more bigger your paper will be, the more time it will take to finish it. I prefer take 9 x 12 (inch)paper so in one hour student will be able to finish it and will learn so many skills as well. 
 
one big brush, one medium wide brush, one thin brush, cup of water and Paper Towel . 

Pencil to sketch, rubber, color marker (Black) or Black (Pen or Pointer)

Basic watercolor paints: ( Blue, white, pink, purple, red, yellow, green, brown, black)

Learners will not need to use any apps or websites beyond the standard Outschool tools.