The most obvious place to look is the internet: Google images for example. However this may not return as many hits back as you might like, and if you're looking for a way to do the hairstyle you might want a website with instructions or something instead of just the image. You could try www.kids-hairstyles.com too: It gives hairstyles for both girls and boys. There are galleries of pictures to scroll through and find ones you like; you can comment and rate pictures as well. Not only this, but there's a gallery of celebrity kids' hairstyles as well. Plus, there are articles to help with taking your kids to hair salons or teaching them good hair care.
You could also flick through some magazines to see if there are any pictures there: Teen or pre-teen mags might be the best as they may include pictures of children around that age, whether they are posters of 'child stars', or maybe kids/teenagers modelling clothes with interesting hairstyles to match. There are specific hair magazines too but most are aimed at adult styles, not ones for kids.
You could also flick through some magazines to see if there are any pictures there: Teen or pre-teen mags might be the best as they may include pictures of children around that age, whether they are posters of 'child stars', or maybe kids/teenagers modelling clothes with interesting hairstyles to match. There are specific hair magazines too but most are aimed at adult styles, not ones for kids.