Don’t be mislead by the title of this site. You are not required to download any software, and the math resources here are fun and free. Although primarily designed for middle and high school students, there seem to be a lot of activities that could be used in upper elementary – and it would be a great site to refer to for extension activities.
The first thing I discovered when exploring the site was the “Starter of the Day” link, which gives a mathematical brain teaser for each day of the month. Below is the example for today:
Shine + Write has many activities that would be great to use with an interactive white board. This “True or False” game, for example, takes some thought. Fun Maths has a page of games and math tricks that will be sure to entertain. Investigations offers challenges that might be good for gifted math students to work on independently.
There are many other links on Transum Software that you may find useful. If you are looking for a way to make math class more exciting, I highly recommend checking out this site.