I know. I know. Valentine's has come and gone, but this is a project that is EASILY adapted to any burst of creativity. Learning about clouds? Rain? Moon? Stars? Flowers? You name it. You can make a mobile out of it. You'll need:
Colored paper
Crayons or paint
Long, thin supports
String
Scotch tape
1.  Cut out paper into whatever shapes you want.  Kids can color it, paint it, etc.
2.   Attach string securely (aka tape generously) to the ends of of your  supports (I just used colored pencils...it's not like this mobile will  hang in your house for years to come) and tape the cut-out shapes to the  string.
3.  Tie another string in the  middle of the support, don't secure yet.  Hold up the mobile and slide  the middle string back and forth until it balances at its fulcrum (yes,  we're talking simple machines/levers here).  Tape string securely into  place.
4.  Work your way from bottom to top, making the mobile as elaborate as you'd like.  
5. Hang up your child's mobile for all to see.
5.   Gush over how awesome it looks to anyone passing by.  Make him/her  agree with you.  Because really, mobiles are the BOMB of all hanging,  preschool art projects, right?
-original idea from...whoever first invented the mobile, I guess.
