I have found a brilliant way to change/improve a technique that a child does not realize effects their playing to a huge degree. Most kids are competitive we must concede, and if you can use that to their advantage in a good way so that they are competing against themselves you are on to a winner!
I like to choose one habit that needs improving to focus on from time to time - lets say a scratchy bow from my previous post, and then I bring it to my students attention.
I then say, lets play through your piece, and we will start with 5 points (5 stickers if more bribery needed). Every time they press too hard on the string, producing a scratchy sound, I will minus a point! You will be surprised how many kids love this! It's like a game to them. One kid loved this so much that she wanted to use this system with all of her pieces, and was so proud of herself when she kept most of her points. This also encourages your child to evaluate how they are playing themselves, and not just rely on the teacher or parent to tell them when they are not producing the best sound. My students often volunteer their own criticisms of how they could have played something better after this exercise, and they really start to listen to themselves objectively.
Remember only focus on one technique per practice session so it becomes a fun learning experience and not frustrating.

Happy Practicing!

Most bow sounds that emerge from young learners are less than brilliant, and that's because there is so much to think about and its pretty darn difficult...
The majority of problems come when the bow moves too slowly producing a scratchy sound. I explain to my students that it's like a car with the breaks on, if it's not continuously moving, the car will produce a screechy sound. The bow is like a moving car, it has to keep moving at a continuous pace. The faster the bow, the more brilliant the sound, as long as (and this is important) there is not too much bow pressure! crushing the bow into the string is the other mistake kids can easily make. The string needs to vibrate in order to produce a brilliant sound. If you press to hard the string can't produce a ringing sound. Particularly with chords, a lot of bow is needed, and a fast arm - almost like they are pushing someone away. If the sound is on the other hand too quiet, then they are also not moving the bow fast enough. Lastly, check the bow grip is firm, and the arm is at the right string level. A lazy bow grip means the bows contact with the string will be not as effective, and it won't matter how fast the arm is moved!

Happy practicing!!