TROUBLESHOOTING MATH: You can build a big math program that teaches everything--or just attack the gnarliest problems. Motion Math Games, the guys who brought you the bouncing ball to teach fractions, just released Motion Math Zoom. This latest app exploits the iPad pinch function to explore number sense skills beyond fractions. Co-founder Gabriel Adauto points out that physically "pinching" the screen is a nifty way to improve number sense around decimals, place value and negative numbers. Kids can pinch their way from amoebas (thousandths) to dinosaurs (thousands). Free beta of Motion Math Zoom here here.