Houghton Mifflin Harcourt has launched Curious World, an online subscription service that offers access to a variety of children's interactive digital content for $9.99 a month.

Designed for children ages 3-7, the service is available as a free app and website featuring downloadable e-books, videos and games built around HMH brands like Curious George and The Polar Express.

Curious World is launching with about 500 titles, and new content is expected to be added on a weekly basis. The site also offers content recommendations. A portion of the site's offerings dubbed “playful learning content” is curated by early learning experts at HMH.

The offerings on Curious World are, according to HMH, focused on eight “key learning areas,” such as science, math, language and creative expression. The site also has a dashboard for parents that allows them to track their child’s use of the content, as well as provide feedback on the child's interests and progress.

The service is similar to such kids' subscription services as FarFaria ($3.99/month), Epic! ($4.99/month) and Sesame Street E-books ($3.99/month).

Susan Magsamen, senior v-p of early learning at HMH and senior advisor to the Science of Learning Institute at Johns Hopkins University, said the content on Curious World speaks to emerging research that it is developmentally beneficial for children to learn through play. “Play allows children to explore, to imagine and be curious, building a strong foundation of critical skills for school-readiness and lifelong learning,” she said.