Keeping the bow straight is tough for beginners, usually the tendency is for the bow to follow the natural movement of the arm so it ends up with the tip of the bow traveling over onto the fingerboard (fuzzy sound - not great) or colliding with the bridge (scratchy sound - irritating!). The best way to monitor your bow arm is to practice with a mirror. Aside from that, following the basic principle of pushing your arm slightly in front, and away from you on down bows will keep it more aligned with the bridge and in the golden area for sound. On the up bow, get your child to pretend they are looking at their watch so their wrist bends slightly. This will ensure the bow doesn't travel at an odd angle behind their head. If you are finding it hard to help them with this, I've just discovered a new item available on amazon at the link below called "Bowzo" which slots over the strings and keeps the bow nicely aligned. Probably not best for long term practice, but great for short periods of time to get your child used to the right range of motion!

https://www.amazon.co.uk/gp/product/B00DBWZ7O8/ref=pd_sim_267_5?ie=UTF8&psc=1&refRID=80WJGH06SYP1R9AV2X1N

Happy practicing ;)

Younger kids especially can lose focus easily when they are tired. I can't teach kids too late in the evenings or they literally cannot focus and sometimes break down into tears. You can't make a kid focus when they are in this state, so pick your practice times wisely! Just after school is perhaps another time when they might be in an energy slump, they need a break and food - depending on the child of course. This leaves early evening and the mornings for practicing. With increasing demands on homework for school, It might be effective to try making it a habit to practice before school in the mornings when their minds are alert and fresh. I woke up and did this in my school years, and now the students of mine that are keeping their practice habits are finding this works for them also. There's the added advantage that its then done for the day and they can relax and focus on their other activities when they get home from a long day. It doesn't have to be a very long session, but it starts getting them into the habit, making progress and when they see the results, it encourages them further. Try it!

Happy practicing :)