StoryLine can help in improving kids pronunciation way better than many other tools you might be using.I have been tweaking around with some of its features and just found it awesome. It has a quick loading time and offers a good user interafce that is full of shining colours to attract kids attention.
There is a wide range of stories to choose from and once you find the one you want to listen to you can then select which internet connection you have whether it is small , medium and large then you hit play and there you go. What is even cool about this website is the accompanying activities each audio has. Kids will have post and pre listening questions to answer which is a sort of comprehension check.
Head over to StoryLine and give it a try