This product has both a black& white version and a color version. One set of cards involve students recognizing the number of degrees in either supplementary or complimentary angles and then just adding/subtracting to determine the missing measure. On the other set of cards students will need to use a protractor to measure at least one of the angles before determining the measure of the other angle. Realize that not all protractors are precise – so measure to the nearest whole number. If students are off 1-2 degrees – I wouldn’t be concerned. Just make sure the total is either 90° or 180°. Choose which set of cards are most appropriate for your class.