Looking for a way to boost your second grader's two-digit addition skills that's not a total bore? We've got the answer for you: A super hero-themed worksheet that even includes a puzzle at the end. Solving these double-digit addition problems will lead her to the name of the super hero's mystery code name ... and boost her mental math skills, too!

Want more? Download and print the rest of the worksheets in this series for more math fun.