I taught classroom keyboarding to my 4th and 5th grade students for 24 years. I discovered many things that helped them succeed. Whatever method book you use, the notes and staff are too small, there is too much busyness on the pages, and too many crutches (numbers and letter names of notes). I kept my 30+ copies of the book I was using, but re-wrote the first 15 pages using PrintMusic, making the staff and notes large, with no words (or crutches ) on the page and then had them "graduate" to the big books (published books) when it was time to add single finger chords and rhythms on the electronic keyboards.
I used the resource you see here as an introduction and review for several weeks before they began to use their headphones for private practice.
I REQUIRED the students to sing the notes as they played for me before I would pass them on the the next song. (yes, they could play 2 or more songs, if they were ready). The great joy for them was when I asked them to "sight-read" the sixth or seventh song, and they were amazed to discover they could do it!