STEM
BoneTots
Bones for ages 3–5: build a skeleton — tap a bone, tap where it goes, and each bone tells you its job. Then find out how big it is, measured in YOU! Dinosaurs, herons, catfish, and you. Slow and calm; on-device.
▶ Play it nowBuilt for sittings of about 10 minutes on the screen. That is our design budget, not a measurement.
Meet your mentor
Every Spark & Anvil app has a friendly mentor character that demonstrates, asks, and patiently scaffolds learning.
Mentored by Marrow
#a16207 Characters who teach
Meet the cast
BoneTots's little cast each keep one bone and its job; Marrow the friendly skeleton knows every bone has a task — and that even a giant T. rex can be measured in kids.
Marrow
the friendly skeleton — every bone has a job, and everything can be measured in YOU
Cranny
The skull — keeps the brain safe (structure protects function)
Spine
The backbone — a stack of little bones so the body can bend and stand tall
Cagey
The ribs — a cage that keeps the heart and lungs safe
What's inside
Learning goal
Bones for ages 3–5: build a skeleton — tap a bone, tap where it goes, and each bone tells you its job. Then find out how big it is, measured in YOU! Dinosaurs, herons, catfish, and you. Slow and calm; on-device.
Mentored by Marrow — no data leaves the device.
How BoneTots handles your kid's data
- ✅ All progress, settings, and AI-generated content stays on the device
- ✅ No analytics, no tracking, no third-party SDKs
- ✅ Free — no ads, no in-app purchases
- ✅ No personal information collected from children — in line with COPPA (updated by the 2026 FTC amendments)
- ✅ No chat with strangers — play-together rooms use a short code and preset emotes, never typed messages