As we’ve reported before, our good friends over at Google are starting up a daily puzzle challenge. Each day’s puzzle will task your googling skills a little more, leading you to Google mastery. And much to our enjoyment, they’ve decided to share the puzzles with us at GeekDad (hmm… Google a Day? GD? GeekDad?), so each morning at 12:01am ET you’ll see a new puzzle, and the previous day’s answer (in invisitext) posted here. SPOILER WARNING: As a test, we’re going to leave the comments on so people can work together to find the answer. As such, if you want to figure it out all by yourself, DON’T READ THE COMMENTS! Also, with the knowledge that because others may publish their answers before you do, if you want to be able to search for information without accidentally seeing the answer somewhere, you can use the Google-a-Day site’s search tool, which will automatically filter out published answers, to give you a spoiler-free experience. And now, without further ado… TODAY’S PUZZLE:

Können Sie die Bevölkerungsdichte der größten Stadt in Deutschland finden?

YESTERDAY’S ANSWER (HIGHLIGHT TO SEE):

Search [vision test]. Find that it is typically done with a Snellen chart. Search [Snellen eye chart] and learn that it was developed by Dutch ophthalmologist Hermann Snellen in 1862.