Parents pass characteristics and traits to their offspring.  That's why children often look like their parents.  The mechanism of how  characteristics are passed from generation to generation was a mystery until just 150 years ago.  AT that time, a Monk named Gregor Mendel (considered the father of modern genetics) experimented with pea plants.  Mendel was trying to determine how characteristics were passed to offspring.  He looked at pea plants because they were available and he could grow many of them in the monestary gardens.

So, what did he do?

Mendel had some pure strains of peas that always produced the same characteristics in their offspring.  He had tall pea plants that always produced tall offspring, and he had short pea plants that always produced short offspring.  He wondered what would happen if these two pea plants were corssed (bred together)?  So he tried this.  He carefully crossed male tall with female short, and short male with female tall plants and planted the seeds. 

Pure short pea plants                                     Pure tall pea plants


Consider the following:

There are a few possible outcomes from this experiment:

1. Sarah says that all the pea plants would

   be tall because the tall characteristic is

   stronger than the short characteristic

2. Mina says that Sarah is wrong, all the

    plants will be short because short 

   characteristic is stronger than tall.


3. Becky says that they are all wrong, the 

    peas will be medium, because the

   characteristic will blend.

4. Samuel says that the pea plants that the

   father's characteristics will show, and

   that the female characteristics won't. 

   That means that half the plants will be

   tall and half the plants will be short.



Sarah                     Mina                  Becky                        Samuel

So, what do you  think?

Each student has expressed their ideas about the expected outcome, and given reasons why they expect the results they do.

Who do you think is correct?  What is it about their argument that convinces you?