Tablets designed just for kids are getting more sophisticated as they face increased competition from regular tablets. The new products also have better screens, speedier chips and fashionably slim bodies. Although many of the tablets were originally conceived as educational toys for kids as old as middle schoolers, older kids have been apt to reject them in favor of their parents' tablet or smartphone. That shift has prompted companies to focus more on preschoolers and kindergarteners, as they create super-durable products that can withstand repeated abuse and develop games and apps that teach reading and math. But now, some of those companies are looking to take back some of the sales to older kids that they've lost over the years, offering premium products that look and perform less like toys and more like the ones adults use.