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In this genetics activity, learners create imaginary creatures known as "Reebops" to explore the relationships between genes and inherited traits. Using Reebops as a model, learners investigate how hereditary information is passed from one generation to the next, and how the physical appearance of offspring is determined from the combinations of genes received from parents. This activity guide includes detailed background information, glossary, and handouts. [Activity is publicly available through a web crawler capture on]

Quick Guide

Preparation Time:
30 to 45 minutes

Learning Time:
1 to 2 hours

Estimated Materials Cost:
Over $20 per group of students

Age Range:
Ages 8 - 14

Resource Types:
Activity, Lesson/Lesson Plan, Model


Materials List (per group of students)

  • 120 large white marshmallows (2 bags)
  • 300 "mini" colored marshmallows [pastel colors: pink, green, orange, yellow] (1 bag)
  • 34 fancy toothpicks with fringe (same color)
  • 140 [approx.] plain round toothpicks
  • 32 red flat thumb tacks
  • 32 green flat thumb tacks
  • 60 clear push pins
  • 68 red push pins
  • 17 brown pipe cleaners (each cut in half)
  • 45 legal size envelopes
  • Roll of black yarn
  • Roll of yellow yarn
  • 15 sheets of white "Karyotype" chromosomes
  • 15 sheets of pink "Mom" Reebop chromosomes
  • 15 sheet of blue "Dad" Reebop chromosomes


  • Life Sciences
    • Heredity and Genetics
      • Patterns of Heredity
      • Human Genetics
      • DNA Structure and Function
  • Mathematics
    • Data Analysis and Probability
      • Data Analysis
      • Data Collection
      • Data Representation
      • Probability
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations
      • Gathering Data
      • Formulating Explanations
      • Communicating Results

Informal Categories

  • Food and Cooking


To use this activity, learners need to:

  • see
  • see color
  • read
  • touch

Learning styles supported:

  • Involves teamwork and communication skills
  • Involves hands-on or lab activities


Access Rights:

  • Free access


  • Soderberg., Patti


  • All rights reserved, Center for Biology Education, University of Wisconsin-Madison and Patti Soderberg, 1991

Funding Source:

  • Howard Hughes Medical Institute