Keeping practice fun
Children will spend hours doing what fascinates them, so it is worth spending some time coming up with ways to make practice interesting. Toys, games and charts all have their place but I suggest you use them as sparingly as possible both to keep their novelty (for when you really need them!) and so as not to lose sight of the real goal of learning to play music. I call any activity that is included just for fun, a "side-activity". Keep a list of side-activity ideas because none of them will work forever!
Below, there are two lists. First is a list of general ideas for interesting ways to run a practice session. Below that is a list of ideas for repetitions because repetitions are essential to automate any skill.
General ideas for practice sessions:
Before the practice session, get the child to prepare a lego creation that can be broken into some number of sections. Gradually put the creation back together, adding another component each time one of the practice items is completed.
Before the practice session, get the child to prepare a doll and some doll-clothes. Gradually dress the doll, putting on one item of clothing after each practice item is completed.
Child as teacher
Get child to be the ‘teacher’ while you (or another adult, or a fluffy toy) try to do whatever the child is supposed to be learning.
Try making practise into a time of experimentation and discovery e.g. “Let’s see how many times in a row your hand can play that little part correctly. You play and I’ll count”.
Fluffy toy as "checker"
Get a fluffy toy to be the ‘checker’ checking a particular aspect of posture or playing.
Do it both ways
Sometimes a child will do something the "wrong" way just because they can't do it the "right" way and they don't want to admit it! Tell them that they can choose which way to do it in the piece (for now) but you would like them to show you that they CAN play it both ways.
Make a video
Take a video of your child playing their instrument. This can be very enlightening for them and you.
Fluffy toy Concert
Invite some fluffy toys to come and watch a concert of review pieces.
Read a book
Read one page after each item
Sometimes children go through a phase where they can’t accept instruction of any kind from their parent. This can be hard! But sometimes they will accept a running commentary. Perhaps they will play for you as long as you don’t ask them to do anything, and perhaps you can get away with reflecting (a lot) on what they are doing. Perhaps you could bring a few fluffy toy “children” along to listen. Maybe the fluffy toys are also learning music, then you can chat to them about what you're seeing and whether they find that aspect difficult as well. Perhaps they can learn something from watching your child play. This could all be done without actually "asking" your child to do anything.
For a violin child who keeps moving away to sit down between each piece
Write a secret note for them saying something nice like “I love spending time playing music with you”. Fold the note and get them to put their foot on it while they practice. If they can keep it covered till the end of the practice they can read the note. If they leave it uncovered you can take it away and they will never know what it said.
Violin children can play in different places
Play outside, or in a different room
To help repetitions go smoothly it can help to have another activity going at the same time. Often the best motivator is whatever the child’s current favourite toy or activity is. Think laterally about a way to include this in your music practise
Check that the child can actually do the thing you are asking first. Or can use repetitions as just attempts but if child can't actually do the thing yet, they probably won't tolerate repeating something that they can't do for long. Better to make the task easier so they can repeat something that they can do.
Build a block tower
Add one block for each repetition. How tall can the tower go?
Counters moving across
Use some little items as counters and move one across each time a correct repetition is played.
4 corners (for violin)
Learn to play a short section facing the usual direction. Get the child to turn around 90 degrees then play the section again. If it is correct, turn another 90 degrees and repeat. If not correct come back to the start. Can they do it 3-4 times correctly in a row, to get all the way around?
After each correct repetition, draw part of a picture. How many will it take for your child to guess what it is? Or let your child choose what you will draw.
For piano, the child could play a repetition in each octave
Set up a toy car at one end of an area. Set up a few stops along the route (could be across the top of the piano). Choose a short section of music to be practiced. For each completely correct playing (pauses allowed but no wrong notes) the car moves one stop further along. If there are any wrong notes the car goes back one stop. Can your child get the car to the other end?
Violin stations route
Make some stations defining a route, perhaps squares of coloured fabric or cushions on the floor. Play a repetition standing on each square. If correct move forward one square, if not, go back one square.
Have the child do each repetition doing a different physical thing; e.g. sticking out tongue, one eye closed (or both), standing on one foot (for violin) etc. The playing must still be correct!