All good science starts with becoming familiar with current established knowledge of the field of study. Read books, magazine articles and websites regarding how blood type is passed from parent to child through heredity. Look into which blood types are possible and not possible in the offspring given the parents' blood types. Set yourself a challenge to type anonymous parent and child blood samples and match the children with couples that could potentially be their parents. Alternately, ask whether the parent and child could donate blood to one another in a life-threatening situation.
A hypothesis statement makes an educated guess or prediction about the results of an experiment. Write a description of what you hope to accomplish through the blood typing experiment. For example: "I will match children to parent blood types to determine whether family members have compatible blood types for blood transfusions in case of emergency."
Take blood samples from at least five to ten couples and their children using a home blood-typing kit. Include subjects of different racial and ethnic backgrounds to compare whether certain blood types appear more frequently in people of different races and ethnicities. Label each sample with a secret code and record it with the name on a separate sheet but keep the samples anonymous during the analysis phase. Clip each couple's cards together but keep the children's samples separate from the parents'. Compare each child's blood type with each couple. Make a chart that indicates whether each couple's blood type combination could have produced this child's blood type. Alternately, compare the blood types within each family and determine which members could safely donate blood to one another.
Any knowledge gained through science is only useful if communicated to others for their benefit. Write up a summary of the research, objective and hypothesis and testing procedure. Make charts and graphs of the results. Create a family blood type compatibility chart for each family and provide it to the family for their medical files. Describe what you learned from this project, the limitations of blood typing in determining ancestry and what recommendations you would make for more accurate parent-child matches. Arrange all the written pieces and visuals neatly in chronological order on a tri-fold science fair display board.