Mass: Equal-Arm Balance  Matter is anything that has mass and
takes up space.  Mass is defined as the amount of matter that an
object is made of.  YIKES! Matter has mass and mass is made of
matter!  This doesn’t  tell me what these terms mean.  UUM!! For
now, let’s say that  mass is the amount of STUFF that an object
is made of.  For example, in the diagram of the equal-arm
balance, Objects are placed on each pan of the balance. On the
left side (A) , the mass of the green object is unknown. On the
right side (B), the mass of the purple object is known and its
marked as 100 g.  This measuring tool is balanced when the arm
is parallel to the ground. When balanced, the mass of the
objects on each pan are equal. For this diagram, the unknown
mass is equal to 100g.  NOTE: The arms on each side of the
balancing point (middle where red triangle touches) are equal.
Discover for Yourself  You can make an equal-arm balance using
common materials. For example, in the diagram a ruler is used
for the arm of the balance.