General Math practice websites:
Fact Fluency (MY FAVORITE for those who are still not quite fluent in their facts)
mathgames.com (skills practice)
Number Blocks YouTube Videos (Grade 3 math concept videos - multiplication, etc)
Online games to practice 2 and 3 digit number sense (*ABCYA.com free on PC):
Math Bingo (tens and ones, or hundreds, tens, and ones)*
Comparing Number Values (whole numbers, medium level)*
Guess the Number (1-100)*
Place Value Hockey (level 1)*
Place Value Party (level 2 or 3)
COINS!!! A great way to practice mental computation (addition) is using coins - real ones preferred. Hand them a pile and have them determine how much money. There is also online coin games:
www.usmint.gov/learn/kids/games/counting-with-coins
www.abcya.com/games/break_the_bank_sorting
www.abcya.com/games/money_bingo
mrnussbaum.com/money-tree-online-game
www.math-play.com/coins-game/Counting-Coins-Matching-Game.html
*Be sure to practice activities above (place value) before doing activities listed here*
Addition/Subtraction
2 digit
3 digit
Multiplication
2 and 3 digit mental math practice - online games