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Step-by-Step Procedure:
Day 1:
1. Present case study and have students fill in this chart as a way to document their discussions.
2. A review lecture on blood typing and punnett squares with reminders for students to wear appropriate lab
gear for next class.
Day 2:
1. Students perform blood typing and will need: 4 plates (2 baby plates, one for each possible father)
2. Students should use separate toothpicks for each well in a plate and different toothpicks for each blood typing plate.
3. They should add about 3 drops of blood and 3 drops of antisera to each well. A labeling system for students could be useful
such as chalk markers to write on lab tables or placing the blood typing plates on white paper so students can write labels.
4. Students will document their findings and come up with a conclusion and write up for the case study. Circulate around the
room and discuss with students
Expected Results:
This is an instance of Heteropaternal superfecundation. This means that Josh fathered Baby 1 and Billie fathered baby 2.
Allysse had two eggs mature within 3 days and the eggs of each baby were fertilized by separate sperm from different fathers.
Disposal/Clean-up:
When washing blood typing plates—be sure to dilute blood components with lots of water. They may coagulate in your sink.
If possible, putting liquids into a disposable plastic water bottle before rinsing off residue from your glassware will prevent
coagulation in your sink.
Extension:
• Using phlebotomy arms for practicing a blood draw
• You could introduce ethics, birth control methods and legal issues as part of the discussion on the case as ways to build up
the lesson into a larger unit.
Enriching Case Studies with Hands-On Lab:
Blood Typing (continued)
Facts— What facts can you get from
the case? Gender, age, problems,
symptoms, diseases, blood
work, family history, etc.
Hypothesis? Based on the facts, what
do you think is going on in the case?
Support hypothesis with a + or if they
are refuted at later time (–)
Questions— What questions
do you have? What additional
research topics does your
group need to do?
Answers to the
research questions.
Baby 1 Baby 2 Baby 3 Baby 4
A B A B
