Problem: Article: Once your floor is cleared of any risky objects, you can lay down padding for your guinea pig to play on. Bath mats, old blankets, and towels, or the newspaper can protect your floor and provide a comfortable play area for your guinea pig. With tile or linoleum, put down anti-slip mats first to prevent your blankets or towels from shifting around. If your guinea pig is exploring a bedroom or office, close the door to this room. This will prevent your guinea pig from getting stepped on, running into other house pets, or chewing on objects that are off-limits in the rest of your home. A short, foldable wire fence often sold in pet stores can be used to set up a safe play space for your guinea pig. It can be used indoors in any guinea pig-proofed room, or outdoors to give your guinea pig fresh air and grass to explore. Make sure all other pets are locked out of the room before you allow your guinea pig out. This will help keep your piggy safe. Giving your guinea pig supervised "floor time" out of its cage will help keep it happy and healthy. By giving your guinea pig its toys and playing with it often, your guinea pig is less likely to be drawn to household items that should not be chewed. Examples of toys include small chew toys made from hay or sticks, tunnels, or miniature tents. Hay or stick toys will let them chew on safe objects. Tunnels and miniature tents let them hide, which they love to do.
Summary: Prepare a clean, padded floor for your guinea pig's play area. Close doors to other rooms to let your guinea pig explore safely. Set up a pen in a common area if it doesn't have a designated room. Keep your guinea pig mentally stimulated and happy with toys.

In one sentence, describe what the following article is about: Atomic mass, the mass of a given atom or molecule, can be expressed in standard SI mass units - grams, kilograms, etc. However, because atomic masses, when expressed in these terms, are incredibly small, atomic mass is often expressed in unified atomic mass units (usually shortened to "u" or "amu") or in Dalton's (Da). The standard for one atomic mass unit is equal to 1/12th of the mass of a standard carbon-12 isotope. Atomic mass units tell the mass of one mole of a given element or molecule in grams. This is a very useful property when it comes to practical calculations, as it allows easy conversion between the mass and moles of a given quantity of atoms or molecules of the same type. Most standard periodic tables list the relative atomic masses (atomic weights) of each element. This is almost always written as a number at the bottom of the element's square on the table, under its one or two letter chemical symbol. This number is usually expressed as a decimal rather than as a whole number. Note that the relative atomic masses listed on the periodic table are average values for the associated element. Chemical elements have different isotopes - chemical forms that differ in mass because of the addition or subtraction of one or more neutrons to the atom's nucleus. Thus, the relative atomic mass listed on the periodic table is suitable as an average value for atoms of a certain element, but not as the mass of a single atom of that element. Relative atomic masses, as listed on the periodic table, are used to calculate molar masses for atoms and molecules. Atomic masses, when expressed in amu, as on the periodic table, are technically unitless. However, by simply multiplying an atomic mass by 1 g/mol, a workable quantity is obtained for an element's molar mass - the mass (in grams) of one mole of an element's atoms. For example, the atomic mass of iron is 55.847 amu, which means one mole of iron atoms would weigh 55.847 grams. As has been noted, the relative atomic masses listed for each element on the periodic table are average values of all of an atom's isotopes. This average value is valuable for many practical calculations - like, for instance, calculating the molar mass of a molecule comprised of several atoms. However, when dealing with individual atoms, this number is sometimes insufficient. Because it's an average of several different types of isotopes, the value on the periodic table isn't the exact value for any single atom's atomic mass. The atomic masses for individual atoms must be calculated by taking into account the exact number of protons and neutrons in a single atom.
Summary:
Understand how atomic mass is represented. Locate atomic mass on the periodic table. Understand that periodic table values are an average atomic mass for an element.