1. Rules for Constructing Isolines
They connect equal values
They should go off the map or form a loop
They never Split or Cross
They are almost parallel
They separate bigger and smaller values

2. Steps for Constructing Isolines
Lightly circle all of the values that are equal to the line you are constructing in pencil
Draw light pencil lines between values that the line should be between
Connect your circles and your lines
Follow those steps and construct the isolines roughly parallel

3. Temperature and Pressure
Isotherms connect equal temperatures and they run across the country from west to east
Isobars connect equal pressures and they will form loops around high or low pressure centers