A while ago I came across an interesting language learning-related idea but then promptly forgot where it was. I finally found it again today here. The idea is that you record yourself speaking the language(s) you’re learning every so often, then go back to the recordings later to see how much progress you’ve made. These recordings could be said to be linguistic time capsules.
If you’ve learning to play a musical instrument or to sing, you could make something similar – a musical time capsule.