free complete Unit Studies through Educents through tomorrow, both for kids 8-13: "Curiosity Files" and "WannaBe Series."
I've downloaded both of these, and though I haven't yet gone through any with my child (he's a little younger...so I'm saving them for later), they look GREAT. These are FULL UNITS, and are very thorough.
The Curiosity Files include in depth units on all sorts of interesting scientific topics, such as Vegetarian Spiders, Blue Diamonds, Rogue Waves and Quicksand. Though the focus is the science, they include vocabulary, creative writing, handwriting, Bible Study and in some units even a little geography and history.
The "Wanna Be" series is similarly in depth, and don't let the name fool you--this is NOT for younger kids. Its a serious look at various carreers, including pilot, video game designer, veterinarian, missionary, farmer, military personnel, police officer, firefighter, doctor, artist, and chef. If your child is interested in any of these fields, these units would be great for them to explore.
Disclosure: This post contains my affiliate link to Educents