1. White Eyes female x Eyeless male
2. predict the phenotypes of the F1 males and females
3. test prediction by Chi squared analysis.
4. then cross an F1 female with an F1 male
5. predict the phenotypic ratio (show branch diagram to explain why you predict this ratio), show results and test with Chi square analysis.

Note that in most cases, the fly that you design is going to be true breeding (homozygous). However, in some cases that will not be true. If the results of the reciprocal Parental crosse do not produce any of the expected results, then cross the affected F1 by affected F1 and come up with a hypothesis to explain the ratio observed and test that hypothesis with Chi squared analysis. If rejected by Chi squared repeat untill you come up with a hypothesis that is accepted.