I am a Christian. I was an 8th-grade American History teacher. I am currently a freelance writer, public speaker, & homeschooling mom of 9.
Use M&M's to determine genetic traits, extract DNA from a strawberry using normal household materials, create edible DNA strands using marshmallows and licorice, design dog breeds as you select alleles, and more in this fun lesson on Genetics! Use this lesson on its own, or add it to the Human Anatomy Unit Study. This lesson is geared toward elementary-age level children and should take about 2 1/2 hours. Use this fun lesson with your classroom, family, after school program, camp, or homeschool group!
1. Pray. Read and discuss Psalm 139:13-17.
2. Read You're Full of Genes by Claudia Zylberberg or other introductory book on genes.
3. Briefly discuss the role and composition of DNA.
4. Give each child a sheet of wax paper or a napkin, the licorice, toothpicks, and marshmallows. Make edible models of DNA strands by following the directions at teach.genetics.utah.edu . Each color of marshmallow will represent one of the four types of chemical bases are: adenine (A) = green, thymine (T) = pink, cytosine (C) = yellow, and guanine (G) = orange. Remember that A always pairs with T and C always pairs with G. They can follow the sequence of T A C G T A T G A A A C by inserting pairs of colored marshmallows on each rung of toothpick and attaching the toothpick to the red licorice backbone. Be sure to give children a few extra marshmallows because some will inevitably be tasted. Have the children set these aside in plastic bags (with names written on them) to go home. (Yes, we did use colored marshmallows. The pastel colors didn't show up well in the photo.)
YOU WILL NEED PER CHILD: small sheet of wax paper or napkin, 2 pieces of red licorice, at least 12 toothpicks, at least 10 of each different color of small colored marshmallows (orange, yellow, pink, & green), and a sandwich bag
How to See DNA
5. Demonstrate the length and width of a strand of DNA.
a. Have 2 children stand at one end of the room and hold out a thin piece of thread that is about 1 meter (3.28 feet). (They should be far enough away so that the other children can't see the thread.)
b. Tell the children that the thread is about the same length of a strand of our DNA, which is about 1 meter or 3 1/4 feet. Ask the other children if they can tell what color the thread. Ask if they can even see the thread. The thread is like DNA. Normally we can only see it with a microscope because it is so thin.
c. Tell one of the children to crumple up the thread and hold it in the palm of his/her hand. Ask the children if they can see the thread now. We are going to do something similar to the DNA in our strawberries so that we will be able to actually see it!
YOU WILL NEED: a piece of thin thread that is about 3 1/4 feet long
6. Follow the directions to extract DNA from a strawberry using normal household materials:
- Give each child or pair of children a strawberry and a plastic bag. Have the children put the strawberry in the plastic bag and smash it into a pulp. Tell them that by doing this, they are breaking the cell walls of their strawberry.
- Have a few volunteers assist in creating a class-size amount of the extraction liquid by gently mixing together 225 ml (or 1 cup) of water, 5 g (or 1 1/4 tsp.) salt, and 25 ml (or 5 tsp.) Dawn dish-washing detergent.
- Each child should add 10 mL (or 2 tsp.) of the extraction liquid to their bag of smashed strawberry and then gently smash the liquid together with the strawberry. (They don't want to create suds or bubbles, though.) Explain that the cell membranes are basically made of fat, which is kind of like grease. The dish-washing detergent is going to dissolve the cell and nuclear membranes of the cell just like it cuts through grease in a dirty pan.
- Have each child wrap a paper towel around their finger and then pull it out so that there is an indention in the paper towel. Have them then put the paper towel in a small, disposable cup. They should pour their smashed strawberry mixture into the indention in the paper towel and allow the liquid to seep through the paper towel into the cup. This will take about a minute. If there is not much liquid, squeeze the juice out from the strawberry mixture inside the paper towel.
- Have the children throw away the paper towels and then slowly add 3 ml (or 3/4 tsp.) of very cold rubbing alcohol down the side of the cup. Explain that DNA is soluble in water but not in rubbing alcohol. Rubbing alcohol actually makes the DNA clump together just like we did with the thread earlier.
- Wait a minute or so until you see a milky white blob of DNA.
- Then allow children to use a bamboo skewer to fish out the DNA strand. The can touch it if they would like. They can also save it to bring it home with them.
- Have children clean their hands and then allow children to each eat a strawberry.
YOU WILL NEED PER CHILD or PAIR OF CHILDREN: 90% rubbing alcohol that has been in the freezer for at least an hour, 1 plastic sandwich bag, 1 fresh or frozen strawberry, salt, Dawn dish-washing detergent, paper towel, small disposable cup (like Dixie bathroom cup), 1 bamboo skewer, strawberry to eat (optional), & measuring tools: granulated cylinders and eyedroppers or liquid measuring cup and measuring teaspoon
7. Read Gregor Mendel: the Friar Who Grew Peas by Cheryl Bardoe.
8. Briefly discuss genetic traits.
9. Have children survey themselves and one another to determine the most common inherited traits (tongue rolling, right-handed, dimples, etc.) among the group by using the inventory chart from An Inventory of My Traits.
YOU WILL NEED PER CHILD: the inventory chart from An Inventory of My Traits and a writing utensil
10. Have children observe how the traits are passes through multiple generations by conducting the Pom Pom Gingerbread Activity found at Generation of Traits. (We used M&M's instead of pom poms.) Have the children assign a different color for each grandparent. Combine the 2 colors from each grandparent for each parent. Finally, combine the colors for each parent in a cup and have the children blindly pull two out for each child so that they can see the various combinations. Allow children to eat their M&M's or cereal afterward.
YOU WILL NEED PER CHILD: the Pom Pom Gingerbread worksheet found at Generation of Traits, a small cup, and M&M's or Fruit Loops
Book to read for Activity 7
Genetic Traits: Creating Your Own Dog Breed
11. Have children observe how variations in DNA lead to different traits by following the directions at A Recipe for Traits. Children will select a DNA strip of paper that will assign them different traits for their dog (such as curly hair, straight & long hair, straight & short hair, or wavy and long hair). They will draw their dog according to the traits they select.
YOU WILL NEED PER CHILD: a writing utensil, crayons or markers, a sheet of paper, and the strips of paper from A Recipe for Traits
12. Briefly introduce dominant and recessive genes and Punnett Squares. Give each child a plastic egg with a colored candy inside. Each egg should have the color traits of the parents taped to the outside. After the children fill out the Punnett Square to determine the probability of what color of candy is inside the egg, the children will make a guess and then open the egg to find out if they were correct.
YOU WILL NEED PER CHILD: a sheet of paper, crayons or markers, and at least 1 plastic egg with a colored candy inside that correlates to the color traits of the "parents"
13. Five minute review of what we learned.
More Great Picture Books on DNA & Genetics
The Way We Work: Getting to Know the Amazing Human Body by David Macaulay includes nice explanations and illustrations on DNA and genetics in addition to fun explanations on the rest of the human body. Have a Nice DNA (Enjoy Your Cells) by Fran Balkwill was one of our picture book favorite books on DNA. It is part of a series of good picture books on DNA that are all similar but focus on different aspects. Baa!: The Most Interesting Book You’ll Ever Read about Genes and Cloning (Mysterious You) y Cynthia Pratt Nicolson is a long picture book, but we still really enjoyed reading it as it covers many aspects that were not covered in most of the other picture books. We also enjoyed reading additional great picture books including My Family Tree by Paul Showers, Amazing Schemes Within your Genes by Fran Balkwill, DNA is Here to Stay by Fran Balkwill, Gene Machines by Fran Balkwill, What Makes You What You Are by Sandy Bornstein, and Grandfather's Nose: Why We Look Alike or Different by Dorothy Hinshaw Patent. The Cartoon Guide to Genetics (Updated Edition) by Larry Gonick is a 224 page cartoon illustrated book on genetics that is both humorous and through. My oldest son really enjoyed this!
Over the years I have posted over 30 science and social-studies based unit studies, compromised of more than 140 lessons. The unit studies include the Human Body, Simple Machines, Earth Science, Medieval Period, American Revolution, Pioneer Life, Countries of the World, and many more! For each lesson I have included activities (with photos), our favorite books and YouTube video clips, lapbook links, and other resources. I posted links to all of my unit studies and lessons at Fun, FREE Hands-On Unit Studies Hub.
Great YouTube Clips on DNA & Genetics
The Crash Course Biology videos do mention evolution, so you might want to watch them ahead of time before showing them to your children. Surprisingly, the Bill Nye video doesn't mention evolution. Later in the video it does have a brief discussion on the fertilization of a human egg. If you're not ready for that conversation yet, you might want to forward through that part.
More great YouTube Video Clips on DNA & Genetics
Some of these videos do mention evolution, so you might want to watch them ahead of time.
Would you like to teach this way every day?
I use Konos Curriculum as a springboard from which to plan my lessons. It's a wonderful Christian curriculum and was created by moms with active children! You can even watch free on-line videos as Jessica, one of the co-authors of Konos, walks you through a unit. (Look for the Explanation Videos tab.)
If you're new to homeschooling or in need of some fresh guidance, I highly recommend Konos' HomeSchoolMentor.com program! Watch videos on-line of what to do each day and how to teach it in this great hands-on format!
© 2014 Shannon