Hi there. That’s lovely that your granddaughter wants you to teach her. How nice that she has chosen playing trumpet with you over playing computer games, or other things. What a beautiful family activity. That’s how most people learnt to play instruments for hundreds (thousands?) of years – from members of their family. Regarding advice, the peripatetic brass teacher who comes to our school every week to teach a small group of eight year old beginners has them learning from the Yamaha Advantage “Greatest Solo Song Book”: 75 songs using only the first six notes (C to A). I think that’s pretty much all they work from for about the first 18 months, and I think there’s something to be said for playing lots of tunes within a limited range. They will become familiar with how these notes sound, gain experience with reading notes within their familiar range and learn various other aspects of music. If “Hot Cross Buns” and “Merrily We Roll Along”, etc., wear a little thin after a while, accompany the songs with some percussion instruments. They are not expensive (or make your own). Play call and response with her. Muck around with dynamics. Encourage her to practise some pieces until they are memorised and then she can perform a little concert for some friends and family. (You should both dress up for the occasion! It’s a soirée, after all 😀 ). Encourage her to write out arrangements for some of her favourite of these songs. For aural development, she can face away from you while you play a few notes and she can try to play them back to you. Then she can challenge you. Have her join you in playing long notes to the drones. My local trumpet teacher also uses Indian drones that she gets from YouTube. Maybe in this way, you will be able to establish good habits with her within a nice, “safe” range over a decent period of time. Have fun!