Save the planet by destroying the aliens quickly.  Students need to solve addition problems in order to fire the weapon.  This will surely improve their additions skills and fluency.

In this game, students can compete against each other online to see who can get their jet ski to the end, the quickest by answering addition questions.

Looking for a fun and engaging way to help your students review adding 1s, 10s, and hundreds? Look no further than Additionasaurus! This worksheet features a friendly dinosaur character that will keep your students motivated as they work through the problems. With a variety of addition problems that focus on ones, tens, and hundreds, your students will get plenty of practice and be well-prepared for more complex addition challenges.

This website gives a great example of using the commutative and associative properties of addition using Skittles.  There is a video available that will help demonstrate successful implementation.

Image anchor chart meant to demonstrate how to borrow when subtracting 2 to 3 digit numbers.

Multiplication.com has some really good self-correcting quizzes for math facts.  It allows students to take quizzes with visual hints or without them.  Students can practice math fact fluency for specific math facts that they might be struggling with.  When a student is finished it can even print out an image of how well they did.

Here are other links to 

3rd-grade students practice telling time using this worksheet.  There are 9 clocks where students have to either draw the clock face or write down the time that a clock is showing.  There is also 4 subtraction across zeros using 3 digit numbers as a review.

Meet Skip the Squirrel.  Students solve 6, 3 digit subtraction questions to find out which color students will color in the picture with.

In this worksheet, students will review adding three digits together as well as adding three double-digit values together.  It comes with a nice pun about rabbits.

This is a random three-digit subtraction generator that is

Smartboard friendly, with big buttons. Click the reset values button and the program will generate two 3-digit numbers that students can use to reinforce their ability to subtract.  I use this program to generate subtraction questions and students can use whiteboards to solve the answer.  This can also be used to play games like king of the row or relay races.