Came across this site and thought it would be worth posting: a collection of Java applets that let you manipulate objects on the screen to work through various concepts:
http://nlvm.usu.edu/en/nav/grade_g_1.html
A couple of issues:
-The applets look very dated and don’t use the latest interactive web technologies.
-A random collection of exercises like this is exactly what makes math and teaching math so overwhelming to me - no suggested order with which to guide the study from most basic to most complex…
So far, I’m concluding that only Singapore Math materials has a prescribed order of concepts hammered out.
On a different note, I did read somewhere that a key basic concept that young people need to first master to succeed in math is the number line - they need to easily be able to visualize or “glide” up and down a small number line and comprehend the numbers have a sequence - to that end, this same passage recommended a real life number line floor mat or banner that kids can hop along and play games on (probably not unlike hopskotch) - and I found one here:
http://www.amazon.com/Learning-Resources-Step-by-Step-Number-Line/dp/B000BZ6TZO