Puzzles

45 Game - a back and forth game students can learn quickly and easily reply until they see the "magic" numbers

Nonogram or Picross - an online game that encourages logical reasoning

Conceptis Hashi - this is a paper copy you can use; also easily available online; encourages logical reasoning

Conceptis Kakuro - also a paper copy; encourages logical reasoning

Color Coding Numbers Hint: this could, uh, factor into a lesson one day!

4 is a Cosmic Number - encourages failing and trying again and again... builds what I call "analytical endurance"

M, Heart, 8 Sequence you can probably draw them better than me... it is important how you draw them if students are watching... for example draw the left side of the heart first, then the right side of the heart, then the line underneath, and for the M with the slash through it, draw an M first then the slash... when you see it you'll see why :)

Magic Tricks

Guess Your Birthday (explained here)

Adding Random Numbers (explained here)