Tag Archives: Punnett Square

Variation and Inheritance: Punnett Squares

We packed a lot into the short class period today.  To reinforce concepts introduced in the video yesterday but not covered in the reading assignment, we spent today learning and applying the vocabulary of inheritance.  We dusted off the cobwebs from student memories from middle school, reviewing the vocabulary words of genotype, phenotype, alleles, dominant, recessive, homozygous, and heterozygous.  We then applied the vocabulary to an example Punnett Square about eye color inheritance patterns.  Notes from the white board are pictured below:

We then applied these concepts to a Punnett Square worksheet.  We worked through the first two problems together (pictured below), and then students used the remainder of the class period to work through the remaining problems.


Students in 4th period were very interested in learning more about the genetics of eye color.  The NIH Genetics Home Reference website explains the genetics of eye color, complete with references to relevant scientific journal articles.  The Tech Museum of Innovation website has a lengthy article written in more student-friendly language (with graphics!) on the topic.  The article includes a calculator to predict the eye color of your offspring, and even provides evidence about how two blue-eyed parents can have a brown-eyed child (Surprise!  High school genetics is over-simplified!).  The question of traits “skipping a generation” also came up during 4th and 5th periods.  We used problem 1 from the worksheet to explain how a grandparent and a grandchild can both share a trait that “skips” the generation in between.

Reproduction, Inheritance, and Meiosis: Dihybrid Crosses

Students learned to construct and analyze the products of a dihybrid cross (two-trait Punnett Square) today.  We worked through the entry task slide using the white boards and document camera in class to ensure student understanding of the process.  Slides 3-7 of the attached PowerPoint deck were not presented in class, but are included as an example for students needing to review.  Students then had the remainder of the class period to complete the dihybrid cross worksheet.

Reproduction, Inheritance, and Meiosis: Punnett Squares

Students worked with partners to complete a single-trait Punnett Square worksheet.  After working through the first question together (example below), students were presented with slides of key vocabulary and examples of the organisms discussed in questions 8 and 9.  The degree of student collaboration and prior knowledge was impressive!  Students who completed the worksheet early were challenged to construct a 2-trait Punnett Square (exampes below).

Worksheet question 1:



Example #1 of 2-trait Punnett Square:



Example #2 of 2-trait Punnett Square:


Genetics Unit – Lesson 7

In Lesson 7, we learned about the Austrian monk Gregor Mendel and his pea plants.  Mendel’s careful study of how pea plants inherit traits allowed him to predict the existence of genes (he called them “particles”) nearly 100 years before DNA was discovered!  Students then practiced analyzing trait inheritance patterns using a Punnett Square worksheet.

Reminder: Students must upload the final draft of their Task to Ms. H’s Dropbox folder (the Final Draft folder in their class period folder) by midnight tomorrow (Friday, February 14).  Students who upload the Task before the deadline and who receive a grade of Proficient or better will receive a Golden Ticket!