So many companies that create educational products and materials direct their efforts to this very age group. There are enough apps that are supposed to teach the ABCs that you could do a different one each day of the year. But some companies really do a great job when it comes to putting together material. Some of it is freely available, some comes at a reasonable cost. Here are some of my favorites:
National Endowment for the Humanities' EDSITEment! - Containing lesson plans for art, history, literature, foreign language, and more, this site has many options for all age groups.
Smithsonian Education - For a more general site to explore for more resources, try Smithsonian Education. They have something there for just about every subject.
BrainPOP Jr. - This entertaining and interactive site teaches students bits of information on dozens of topics. The site has a membership fee, but it also has some free materials as well. Very highly recommended.
Poisson Rouge - Great for young children, this site has plenty of open-ended play options. It used to be free, but now there seems to be a membership fee.
Starfall - From the basics of the ABCs up through reading, along with plenty of handwriting and story writing along the way, this site is a thorough early literacy site.
NaNoWriMo's Young Novelist Workbooks - With different levels for elementary, middle, and high school, this writing program will get kids creating their own stories in no time.
History and Social Studies
Our Documents - It's never too early to begin learning about the foundation documents that were the basis for the government of the United States. This site has plenty of ideas for integrating them into your classroom.
Smithsonian's History Explorer - With lessons for all grade levels, this site can really bring history home with primary sources and objects, interactives, lessons, and many more resources.
Ben's Guide to the U.S. Government - U.S. Civics for all ages! An animated Benjamin Franklin brings the lessons to kids on their level.
NASA - You might be surprised how much material is available for education on the NASA website, and all of it is available for free. Check out their materials for early elementary, or for any grade. They also have the NASA Kids' Club for kids to play on their own.
Hunkin's Experiments - Put together by the same guy who made The Secret Life of Machines series in England, these experiments will get kids learning about the world around them.
Spangler Science - You can never have too many science experiments. These visuals keep kids engaged and interested in learning.
Scratch - This free and entertaining programming interface teaches kids how to create games, stories, and anything their imagination comes up with by dragging and dropping segments of code.
Classics for Kids - This public radio show has been saved for posterity on a website, teaching kids of all ages about classical music and composers.
Carnegie Hall's The Young Person's Guide to the Orchestra by Benjamin Britten - Here, fun games and activities teach kids about the instruments in an orchestra.
The National Gallery of Art - The National Gallery has put together lessons in art and art appreciation for students of all grade levels.
BBC's Dance Mat Typing - If you need to teach your students how to type, this is a go-to site for where to begin. It's fun, cartoon-y, and it works.
Centre for Innovation in Mathematics Teaching - This UK site has a free maths curriculum that tackles the subject from a slightly different angle.