Litmus "Lecanora tartarea" (Norway, Sweden), "Variolaria dealbata", "Ochrolechia parella", "Parmotrema tinctorum", and "Parmelia". Currently, the main sources are "Roccella montagnei" (Mozambique) and "Dendrographa leucophoea" (California). The main use of litmus is to test whether a solution is acidic or basic. Wet litmus paper can also be used to test for water-soluble gases that affect acidity or alkalinity; the gas dissolves in the water and the resulting solution colors the litmus paper. For instance, ammonia gas, which is alkaline, turn the red litmus paper blue. Blue litmus paper turns red under acidic conditions and red litmus paper turns blue under basic or
Teaching to the test a test over the information at the end of the unit. Typically, these tests aim to make sure that students have memorized a series of procedures, rather than making sure that the students fully understand what they are doing; in other words, these tests are a measure of a student's arbitrary knowledge rather than his or her capacity for logical thinking. Teaching to the test is also frequently used for skill-based learning, like typing or athletics; in this context, teaching to the test is the dominant practice. For one reason, teaching to the test misrepresents how much students really have