Marble slides.  This site has lots of cool science activities using everyday materials.

A marble slide from paper towel rolls - GS Junior Inventor badge Give the girls a box of paper towel and toilet paper rolls and other materials and have them create their own.

Here's a very cool and 3-D way of looking at a multiplication table.

The Map is Not the Territory: Messin' Around with the Commutative Property - I didn't have these materials on hand so we used playdough, spaghetti and cut up straws for this multiplication activity

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