Lock the fixed points first Memorise the lower fixed point and upper fixed point for Celsius, Fahrenheit, Kelvin, Reaumur, and Rankine before you start solving. Check whether the question uses ice point and steam point or a different reference. The trap is plugging 0 and 100 into every scale even when Fahrenheit or Rankine is given. Recognise this topic whenever a thermometer question lists two calibration points.

Use one linear identity for every conversion Write (reading - LFP)/(UFP - LFP) for the given scale and the target scale instead of hunting for a memorised shortcut. Check that the numerator uses the correct zero point, such as F-32 or Ra-460. The trap is writing F/9 instead of (F-32)/9. This topic is hiding inside any new-scale problem with freezing and boiling points provided.

Separate absolute temperature from temperature difference Memorise that Kelvin and Celsius have equal size intervals, so delta T in C equals delta T in K. Check whether the question asks for a reading or for a rise in temperature. The trap is adding 273.15 to a temperature difference. Recognise this version when words like increase, fall, or difference appear.

Handle Kelvin carefully Memorise K = C + 273.15 for readings and remember that zero kelvin is absolute zero. Check whether the question is about school-level conversion or the reference discussion around the triple point of water. The trap is treating 273.16 K as the zero of the Kelvin scale; it is a reference temperature, not the zero reading. This shows up when the statement mixes thermometry language with scale conversion.

Practice equal-reading and odd-scale questions Memorise the classic equal-reading result C = F at -40 and solve at least one invented scale problem where the fixed points are non-standard. Check that your relation stays linear from LFP to UFP. The trap is using direct proportion without shifting by the lower fixed point. Recognise this topic immediately when a question defines a fresh scale like X, Y, or W.