Charles' Law states that for a given amount of gas at a constant pressure, the volume increases when the temperature increases. This type of relationship is called a direct relationship, because they both go in the same dirction. Opposite, when the temperature is decreased, the amount of volume decreases.
Test this out! Obtain syringe from a parent or guardian, preferably glass, but be careful. Next, ask your parent of guardian to heat up some boiling water for you. Place this water in one glass cup. In another glass cup, place water and ice. Set the syringe so it erads 15mL of air, the constant pressure. Next, place the syringe in the ice water for 1 minute, then remove it. Read the amount on the syringe. Place the syringe in the hot water, and let it sit there for 1 minute also. Remove it and read the volume. Did the volume go up or down in cold water? That's it!