Krebs' Class Blogs

Constructing, creating, communicating, collaborating, and thinking critically in grade 5.

Genetics Simulation for Friday


We had a science simulation today about the peppered moth. It was a good way to study genetics, use Punnett squares, and learn about natural selection due to environmental changes.

Here is a very short clip showing the peppered moth in its natural protective lichen surroundings.
ARKive video - Peppered moth camouflaged on lichen

Here is a clip of the darker form of the peppered moth.
ARKive video - Peppered moth

First, students were given a moth showing a light or dark phenotype. The genotype for the wing color allele was written on the back.

Genetic info (genotype) on back. Physical info (phenotype) on front in picture of moth.

They matched two moths together and used Punnett squares to show the possible offspring if those two genotypes reproduced.

Each generation of offspring would be placed on a light-colored background. A small proportion of moths had dark wings, the recessive gene. This dominance of the lighter wings stayed, as long as the lichen protected these moths from predators.

However, when the Industrial Revolution began polluting cities in Britain, the light-colored lichen died. The soot on the buildings and the lack of lichen cover began to give the dark moths an advantage, and they were then more protected from their predators.

Students swooped in (as birds) and picked off some of the moths. On the darker background, the lighter moths were easier to see. By the next generation, more of the moths were dark. Eventually, the dark wings became dominant in the polluted cities of Industrial Britain and in our simulation.

If you have Flash, you can do an online simulation about the peppered moth.

Today, the gathering of samples is much more accurate than it was a hundred years ago, but  the conclusions seem to agree that the change in color is an example of natural selection. Now that air pollution is less prevalent, there has again been a rise in lighter-colored peppered moths in urban areas in Britain.

Peppered Moths PDF used above.

Do you have any more information about the peppered moth that we should know?

Author: Denise Krebs

I'm the chief learner in life's adventure.


  1. Mrs. Krebs,
    I liked using that game. I actually caught more of the moths you are not supposed to catch.

    • I liked the game, too, Deven. I think you meant you caught more of the moths that were camouflaged. Is that true? Why do you think that happened? Were you aiming for those?

      Mrs. Krebs

  2. I thought how in the videos how the moths blended into there surroundings so well was really cool. At school I had recently learned about hereditary and dominent trates in school. Check out my blog at

  3. this post was very interesting and I thought it was sad that all the light-color peppered moths were dying but I thought it was kind of cool how the dark peppered moth gene was a mutation

  4. Mrs. krebs
    I liked the game. In the light forest It was 78% light and 22% dark, 84% light and 16% dark, 89% light moths and 11% dark. I played each one 3 times.In the dark forest 2% light and 58% dark. 37% light moths and 63% dark. 35% light moths and 65% dark.

  5. Mrs Krebs,
    I have learned a lot in your classes. In science we played a game about light and dark peppered moths. I learned that in a dark forest it is easier to spot a light peppered moth and vice versa. Thank you for being our teacher. You taught us that we can all be geniuses and change the world!

  6. Mrs. Krebs, that game was really cool some of the time I also caught the moths I wasn’t supposed to but that only happened once, but otherwise I did it right.

  7. Wow! I learned a lot about peppered moths! I learned that light moths survive against the birds better in the light forests because they have a camouflage that blends in with the lichen. And the Dark moths survive better in a dark forest because they are blended in better. I also liked the game with the Dark and Light forests and the Dark and Light peppered moths. Thank you!
    -Anna S.

  8. Mrs. Krebs
    Very fun game learned a lot about the peppered moths and how they evolved. it was fun learning about moths.

  9. Krebs,
    In science we played a game that taught us more about light and dark peppered moths. I learned that on a dark tree birds will eat more light colored moths and on a light trees birds will eat more dark colored moths.

  10. I learned a lot. I learned that the moth is about 1 1/2 to 2 1/2 in. I liked the game. It was hard to find the moth in its environment. I think that the website you sent us to was a great website. I learned a lot.

  11. Mrs Krebs,
    I learned that Being a dark moth is passed on by genetics and not some chemical reaction. I also learned that they had evolved during the industrial revolution.

  12. Mrs Krebs,
    I really liked playing the moth game. I learned a lot from all the slides. I also learned a lot about Dr. Kettlewell.


  13. I was wondering where you found the website for this activity? Thanks for any help you can offer! I want to do a similar activity for my class in Levittown, PA.

    • Hello Mr. Cristea,
      I kind of made up my simulation, but here are some web sites that inspired me. – This was a good one using hole punch circles.
      Plus the computer simulation linked above.

      I’ve also added a PDF to the blog post of the moth pictures I used. Print the two sides back to back. Then count out enough for your students–about 1/4 of them dark moths. For each three light moths–write bB, Bb, and BB for phenotypes. On the dark moths–write bb. The rest of the phenotype sides will stay blank. Students fill out the Punnet squares and then take four more moths based on the phenotypes on their Punnet squares, writing the phenotype on the back of the moths.

      I hope that helps. I’d love to hear about your class’s experience!

      Mrs. Krebs

  14. Hello Mrs. Krebs and class,

    Genetics is an interesting study and was something I studied while at university. I know of the story of the peppered moth. It is one of the classic examples of how change in the environment can influence survival of individuals.

    As you found, with growing industrialisation, darker moths were harder to see by predators and therefore were less likely to be taken. With coal being the major source of power, you can imagine the dark smoke from fire settling its soot and ash on anything in the open.

    When seeing traits as you studied, it reminded me of something that had interested me in my studies, the recessive gene. When this type of gene was present, it only showed itself if it was inherited from both parents, the ‘bb’ genotype in your Punnett squares.

    An example of a recessive gene can be found in lions of the Timbavati region of South Africa. Those animals that have recessive genes from both parents ‘bb’, have a white appearance. If they are BB or Bb, to use your Punnett square example, they appear normal in colour. The lions aren’t albino, although albinism is also an example of a recessive gene.

    If you want to see what the white lions look like, below is a link to Mogo Zoo in Australia about a two hour drive from where I live…

    They are beautiful animals.

    Teacher, NSW, Australia

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