Beacon Lesson Plan Library

Oops! I Made a Mistake

Kitty Roberson


Students study the causes, effects, and inheritance patterns of sickle-cell anemia.


The student knows that body structures are uniquely designed and adapted for their function.

The student knows that every cell contains a `blueprint` coded in DNA molecules that specify how proteins are assembled to regulate cells.

The student understands the mechanisms of change (e.g., mutation and natural selection) that lead to adaptations in a species and their ability to survive naturally in changing conditions and to increase species diversity.


-Activity 1 Worksheet (see associated file)
-Activity 2 Worksheet (see associated file)
-The Genetic Code Table (see associated file)
-M&M candies (24 per student)
-Raisins (24 per student)
- 2 paper cups for each student (1 containing 24 M&Ms and 1 containing 24 raisins)
-Activity 3 Worksheet (see associated file)


1. Make a copy of PreTest for each student.
2. Activity 1:
a. Several days before beginning this activity, assign each student to find out his or her blood type (if the parents donít have this information, their doctor should)
b. Make a copy of Activity 1 Worksheet for each student.
3. Activity 2:
a. Make 1 copy of Activity 2 worksheet for each student
b. Make 1 copy of The Genetic Code for every two students
4. Activity 3:
a. Prepare 1 cup of 24 M&Ms and 1 cup of 24 raisins for each student
b. Make 1 copy of Activity 3 worksheet for each student
5. Make a copy of the PostTest for each student.


Prior knowledge (for students) necessary for successful completion of this lesson:
1. Mendelian genetics
2. Exceptions to Mendelian genetics (codominance, incomplete dominance)
3. Protein synthesis
4. Calculation of percentages

Before beginning lesson, administer PreTest.

Activity 1
1. Have the students find out their blood types. This information should be available from their medical records if they do not already know. For those students who are unable to determine this information, make up 20 cards - 9 with the letter -O- written on one side, 8 with the letter -A-, 2 with the letter -B-, and 1 with the letters -AB-. (These numbers are based on the percentage of each blood type in the population.) Shuffle the cards and place them face down. Have each student select one of the cards which assigns a blood type for that student.

2. Pass out the Activity 1 worksheet and have the students enter the different combinations of alleles that are possible for each blood type in Column 1

3. Have the students complete Column 2 on the chart showing the number of students in the class with each blood type (A, B, AB, O).

4. Have the students calculate the percent of students in the class with each blood type and enter the information in Column 3.

5. Review the different patterns of inheritance involved with each blood type (dominant/recessive, codominance). Have the students complete Column 4 of the worksheet.

Activity 2

6. Review replication, transcription, translation, and mutations with the students.

7. Pass out Activity Worksheet 2.

8. Have the students divide each of the mRNA sequences into codons.

9. Using the codon chart have the student write out the sequence of amino acids used to construct each hemoglobin molecule.

10. The students will then identify which codon in the sickle-cell mRNA contains the error and circle it.

11. The students are then to identify the type of mutation that has occurred and write a short explanation of how this mutation affects the formation of a protein.

12. Review alleles and Punnett squares.

13. Pass out paper cups (one of each type to each student) and the worksheet for Activity 3.

14. Explain that the M&Ms represent normal red blood alleles and the raisins represent the sickle cells alleles.

15. Discuss the difference in shapes of the two types of candy and how this difference in shapes affects the ability of the blood cells in transporting oxygen, movement in the circulatory system, and in resisting malaria.

16. Pass out Activity Worksheet 3.

17. Using the candy and raisins, have the students set up the following crosses:
a. Homozygous normal parent (2 M&Ms) X parent with sickle cell trait (1 M&M, 1 raisin)
b. Parent with sickle cell trait (1 M&M, 1 raisin) X parent with sickle cell trait (1 M&M, 1 raisin)
c. Parent homozygous normal (2 M&Ms) X parent with sickle cell disease (2 raisins)
d. Parent with sickle cell trait (1 M&M, 1 raisin) X parent with sickle cell disease (2 raisins)

18. Have the students use the remaining
candies and raisins to fill in the Punnett squares. Check the Punnett squares as the students are working on them.

19. Have the students replace the candies on the worksheets with the following letters:
A = normal allele
S = sickle cell allele
Note: students may eat the candy and raisins as are replaced with a letter.

20. Discuss the difference between having the sickle cell trait and sickle cell disease and how these different forms affect the body.

21. Have the students fill out the genotypic ratio and phenotypic ratio for each Punnett square using the following information:
a. AA = homozygous normal
b. AS = sickle cell trait
c. SS = sickle cell disease
NOTE: Explain to the students that the sickle-cell trait (AS) is codominant and is expressed in the same manner as is AB blood type.

22. Discuss the origins and geographic distribution of sickle cell anemia. Also discuss the adaptive advantage of having the sickle cell allele in areas where malaria is prevalent.

23. Administer PostTest.

24. Based on the results of the PostTest, decide which concepts may require reteaching.


Activity Worksheet 1 is a review of knowledge already learned.
Grading rubrics are included on Activity Worksheet 2 and PreTest/PostTest.
Activity Worksheet 3 is a reinforcement of knowledge learned during this lesson.

Optional rubric formats may be obtained from a website for a rubric for formative assessments which is listed under Weblinks. This rubric can be customized to fit your requirements.


Information can be given on genetic counseling and treatment.
The South Florida Blood Banks have a presentation on the sickle-cell anemia that includes information on testing, inheritance, and treatment. (561) 845-2323

Web Links

Web supplement for Oops! I Made a Mistake

Web supplement for Oops! I Made a Mistake
Sickle Cell

A site that allows you to create rubric that can be customized.

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