Choose Two Math Operations Game
This is fun game for elementary grades where you choose two math operations (addition/subtraction/multiplication/division) so that the given equation true. If you get it right, the fish will climb up one step on the stairs! If you get it wrong... the fish will flop down a step (unless it's already on the bottom).
Choose the right operations. Remember to follow the order of operations!  

See also
Math Safe
A fun logical thinking game where you need to use the four given singledigit numbers and any of the four operations to reach the target number, and then the safe opens! It practices the usage of all four operations and also the order of operations. The game suits best grades 4 and onward.
www.homeschoolmath.net/interactives/math_safe_operations_game.php
Free worksheets for order of operations
Free printable worksheets for the order of operations, both in PDF and html formats. Choose from five operations and parentheses. You can customize the worksheets by choosing the number range used, number of problems, and more.
Order of operations: lesson for third grade
A free lesson for grade 3 about the order of operations. For this grade level, the lesson only deals with addition, subtraction, and multiplication.
Online games for the four operations and the order of operations