A change of 20 degrees Celsius corresponds to a change of 38 degrees Fahrenheit, not 68 degrees Fahrenheit. The conversion is based on the relationship that each degree Celsius equals 1.8 degrees Fahrenheit, leading to the calculation of 20 times 1.8. Additionally, 20 degrees Celsius actually converts to 68 degrees Fahrenheit, not 70 degrees. The freezing point of water is 0 degrees Celsius (32 degrees Fahrenheit), and the boiling point is 100 degrees Celsius (212 degrees Fahrenheit), which helps clarify the conversion process. Understanding these conversions is essential for accurate temperature comparisons.