Hey, i am trying to teach accuracy and precision. I understand precision to mean two things. How repeatable measurements are (variation), and how specific measurements are (sensitivity). I am having a bigger problem defining accuracy. Most places i look define accuracy as how close measurements are to some true value. However, there is no 'true' value in science. Only a value that is accepted to be 'true'. How accurate are true values? How do we determine the accuracy of these values?