Alright, crossword lovers and Science Friday fans, it's time to pick up those pencils (or pens, if you're confident!), and dust off your SciFri knowledge: We've got a puzzle for you.

Crossword author Fred Piscop has helped us put together a fun puzzle—complete with several Science Friday-related clues.

Click on the crossword below to download and print the PDF. Once you complete the puzzle, answer the final clue, which can be solved by combining the letters in the boxes containing circles. Here's the clue: Science Friday guest who's appeared in both hours of the show, discussing different topics.

The first 20 of you to send us the solution to the final clue gets a Science Friday goodie! Use the form farther down to submit your answer.

We'll share the completed puzzle and final solution a week from today—but in the mean time, we'll be positing hints on Twitter. Plus, read more about the world of professional crossword constructing, and tune in to Science Friday on September 19, 2014, to hear New York Times crossword editor Will Shortz and constructor Matt Ginsberg talk about cruciverbalism in the age of computers.