Welcome to Aplusmath.com! This web site was developed to help students improve their math skills interactively. 
http://www.aplusmath.com/

Visit our game room and play exciting games like Matho and Hidden Picture...Test your math skills with our Flashcards! Try out the new Math Word Find puzzle. 
Create and print your own set of flashcards online! Try out the Flashcard Creator. See the
Worksheets section, where you can print worksheets to practice offline. 
Try the Homework Helper to check your homework solutions. 

AAA Math
http://www.aaamath.com/

This Site Contains:
Hundreds of pages of Basic Math Skills. 
Interactive Practice on every page. 
An Explanation of the math topic on each page. 
Several Challenge Games on every page. 
Math Problems are randomly created.
 

Here are some sites located in the fourth grade section.
AAA Math Fourth Grade
http://www.aaamath.com/grade4.html

Place Values
http://www.aaamath.com/g4-21c-placevalue-specific.html

Adding three two-digit numbers
http://www.aaamath.com/g4-27-add3-numbers-2digit.html

Adding Hundreds
http://www.aaamath.com/g4-38-add-100s.html#pgtp

Subtraction equations with 2 digit numbers
http://www.aaamath.com/g4-28f-sent-sub2.html

Rounding to Hundreds
http://www.aaamath.com/g4-32-round100.html

Rounding to the Nearest Ten Thousand
http://www.aaamath.com/g41d-round10000.html

Improving an Estimate of a sum by rounding
http://www.aaamath.com/g46a-estsum.html

Multiplication by 4, 5 & 6
http://www.aaamath.com/g4-39b-mult46.html

Multiplication by 7, 8, and 9
http://www.aaamath.com/g4-39c-mult79.html

Multiplication Tables
http://www.aaamath.com/g4-39e-multall.html

BasketMath Interactive© 4th grade level
http://www.scienceacademy.com/BI/

Interactive Mathematics Activities 
http://www.cut-the-knot.com/Curriculum/index.html

Euclid's Game
http://www.cut-the-knot.com/Curriculum/Arithmetic/EuclidAlg.html

At the beginning of this simple game, the applet below displays a board with two numbers. At any time you can use the edit control to input a positive difference of any two numbers already present on the board. The loser is the player unable to make a move. If you wish the computer to move first, check the box "Please start".

Somethings Missing
http://teams.lacoe.edu/documentation/classrooms/linda/algebra/activities/hunt/hunt.html

Can you Balance?
http://teams.lacoe.edu/documentation/classrooms/linda/algebra/activities/balance/balance.html

Edhelper - lesson plans, worksheets and Webquests:
http://www.edhelper.com/cat204.htm

Eisenhouwer National Clearing house (a number of links):
 http://www.enc.org/weblinks/lessonplans/math/0,1544,1-Geometry,00.shtm

Geometry through Art Link:
 http://mathforum.org/~sarah/shapiro/shapiro.introduction.html

The MathForum Library has a number of lesson ideas:
 http://mathforum.org/library/topics/addition/

Not sure where this site has it's origins; the link is a bit long but it
has great links:
 http://www.oswego.org/staff/cchamber/linkscf/subjects.cfm?start-51&code=Math

This one is excellent:  http://www.quia.com/dir/math/

Measurement man is a nice lesson idea:  http://www.successlink.org/great/g12.html

This one is very cool:  http://illuminations.nctm.org/imath/index.html