Marshmallow Meiosis
Reebop Gene Expression Information
Phenotype & Genotype Chart
Phenotype
1 antenna
2 antennae
No antennae
1 hump
2 humps
3 humps
Orange nose
Green nose
Curly tail
Straight tail
2 pink eyes
3 pink eyes
Red legs (4 legs)
Black legs (4 legs)
3 body segments (not
including the head)
2 body segments (not
including the head)
Genotype
AA
Aa
aa
MM
Mm
mm
QQ or Qq
qq
TT or Tt
tt
EE or Ee
ee
LL or Ll
ll
DD or Dd
dd
Supplies and Parts:
Antennae (1, 2, or 0)
Humps (1, 2, or 3)
Noses (1)
Tails (1)
Legs (4)
Body segments (2 or
3;not including the head)
Eyes (2 or 3)
Connective tissue (Use
as many as you need.)
green pipe cleaners - cut into 2 inch strips
Mini-marshmallows
Green or orange tic tacs
Red pipe cleaners- cut into 3 inch strips
Red or black Twizzlers – cut into 1 inch pieces
Regular marshmallows
Pink Good & Plenty
Toothpicks (whole or broken)
Sources: Several teachers have published this activity. Here are two.
 Soderberg, P. (1992) Marshmallow Meiosis. The Science Teacher, 59(8)28-31.
 http://home.ptd.net/~jmbacb/docs/marshmallow_meiosis_teachers_manual.pdf
Name ___________________________________________________
Date _________
Activity: Marshmallow Meiosis/Reebops
Goals:
1. To demonstrate how offspring receive a random selection of traits from
their parents.
2. To explain how meiosis is responsible for the tremendous variation within a species.
Background:
Reebops are imaginary creatures made out of marshmallows and other common items. They
tend to live in discarded soda cans. However, they are rarely seen in the wild as they are
extremely fast. Once you have a male and a female in captivity, your room will soon be filled
with Reebops. They are very prolific and require minimal care. Reebops live quite comfortably in
a covered shoebox with small holes punched in the sides for ventilation.
Reebops help illustrate how meiosis is an important reason for the tremendous variation that
exists in every species. Reebops have only seven pairs of chromosomes, each carrying the
gene/allele for a trait that affects their outward appearance (phenotype). This makes them ideal
subjects for studying genetics and the transfer of traits from parent to offspring. (Many
professional geneticists use fruit flies.) Mom and dad Reebops are heterozygous for all seven
traits.
Materials: (per team of 4)
4 large white marshmallows, 4 pieces of two pipe cleaners in two sizes and colors (long and red
for tails, short and green for antennae), several toothpicks, paper plate, white construction or
printer paper, a small white envelope, a variety of small candies: mini-marshmallows, Tic-Tacs,
Good & Plenty, Twizzlers (black and red), Reebop Gene Expression Information
Procedure:
1. What I Know: Write two sentences describing what you already know about the process
of meiosis.
2. Examine the reebop parents that are on display in your classroom. The pair will serve as
the parents for the baby reebops you will create.
3. Work in table groups of four students made up of two gender teams – a team of two to
represent the male parent and a team of two will represent the female parent.
4. Obtain a sheet of reebop chromosome pieces and cut apart the chromosome pairs.
(Each team of two students is responsible for a set of chromosomes. Blue for male and
pink for female.)
5. Set out the 2 parental sets of chromosomes with same lengths together and
letters facing down.
6. Members of each “gender team” should take turns selecting one chromosome of each
length from each parent and place them together in a “new baby” pile.
7. The baby reebop characteristics are determined by turning over the chromosomes and
encoding them according to the Genotype/Phenotype Chart.
8. Circle the alleles selected for the rebop offspring on your Baby Rebop Chart. Then,
write down the genotype and phenotype of your new baby reebop on the chart.
9. One student from each group should get the materials needed to make their baby
Reebop. (Caution: Do not eat any of the materials.)
10. When completed, display your baby Reebops in a designated “nursery” area.
11. Study all the offspring and note their appearance.
12. What I Observed:
a. Baby Reebop Chart:
Alleles
(circle the allele
combinations
selected)
AA
Aa
aa
QQ
Qq
qq
EE
Ee
ee
DD
Dd
dd
MM
TT
LL
Mm
Tt
Ll
mm
tt
ll
Trait
Number of antennae
Nose Color
Number of eyes
Body Segments (not including the
head)
Number of humps
Tail shape
Color of Legs (4 legs)
b. Reebop Drawing (Include your Rebop’s name.)
Name of Reebop: ________________________________
Phenotype
Genotype
13. Questions: Answer the following questions I complete statements.
a. What similarities exist in the Reebop population - all of the baby Reebops you
and your classmates constructed?
b. What differences exist in the Reebop population?
c. How does this activity demonstrate meiosis – the process that occurs in sex cells
(sperm and egg) by which the number of chromosomes is reduced by half?
d. Gamete cells or sex cells contain half the number of chromosomes. The other
body cells contain a full amount of chromosomes. Does your baby Rebop contain
the half amount or the full amount of chromosomes?
14. What I Wonder: Pose a question about what you may still like to know about the topic of
meiosis.
15. Claim and Evidence Writing Prompts: Use the following prompts to help you construct
your lab conclusion, What I Learned.
 Goal: State the goal of this lesson.
The goal of this lesson is…
 Claim: What did you learn from the activity that satisfies the goal of this lesson?
This is an I Learned statement.
I learned that…
 Evidence: How can you prove from your observations that you learned what you
claim? This can be a general statement that you will explain in detail in your
explanation.
I know this because….
 Explanation: Use specific data from your observations to support your claim and
describe the evidence. Use details to support your claim.
 Concluding Statement: Reword the goal and either add information you learned
about the topic from your text book, class discussions, and/ or personal research
OR you can extend the statement by adding a relevant question.
16. What I Learned: Write at least a one paragraph summary of what you learned from
completing this activity. Use the Claims and Evidence Writing Prompts to help you
compose your summary.
Supplies and Parts:
Antennae (1, 2, or 0)
Humps (1, 2, or 3)
Noses (1)
Tails (1)
Legs (4)
Body segments (2 or 3;not
including the head)
Eyes (2 or 3)
Connective tissue (Use as
many as you need.)
green or any other color pipe cleaners - cut into 2 inch
strips
Mini-marshmallows
Green or orange tic tacs
Red or any other color pipe cleaners- cut into 3 inch
strips
Red or black Twizzlers – cut into 1 inch pieces
Regular marshmallows
Pink Good & Plenty
Toothpicks (whole or broken)
Sources: Several teachers have published this activity. Here are two.
 Soderberg, P. (1992) Marshmallow Meiosis. The Science Teacher, 59(8)28-31.
 http://home.ptd.net/~jmbacb/docs/marshmallow_meiosis_teachers_manual.pdf
Materials for one quad (100 students)
Students work in groups of four to create one reebop baby.
green pipe cleaners - cut into 2 inch strips
Mini-marshmallows
Green or orange tic tacs
Red pipe cleaners- cut into 3 inch strips
Red or black Twizzlers – cut into 1 inch pieces
Regular marshmallows
Pink Good & Plenty
Toothpicks (whole or broken)
1 package or about 25 pipe cleaners
1 bag
4 pkgs of each
1 package or about 25 pipe cleaners
1 package of each
2 packages
1 package
2 boxes of round colored type