Big Pumpkin
Phenomenon:
Every year a contest is held to see who can grow the world's largest pumpkin. The winning pumpkins typically weigh over 2,000 pounds!
Student Task:
Explain how a farmer can grow such a large pumpkin.
Model
Students develop a model of the pumpkin life cycle.
Students use a computer model to grow a virtual big pumpkin, considering the effects of selection and the environment.
Investigate
Students measure the weight of pumpkins and observe variations of traits.
Students investigate how different amounts of water affect plant growth.
Obtain Information
Students read to obtain information about how farmers grow large pumpkins.
Analyze Data
Students use a computer model to collect and analyze data, comparing the effects of selection versus no selection and more or less water and fertilizer over many generations.
Explanation:
The environment can influence the traits of an organism. For example, a farmer must provide water, fertilizer, and sunlight to help a pumpkin grow. But the size of a pumpkin is largely a heritable trait. Offspring inherit traits from their parents. So, a young plant grows to look very much like its parents. A farmer who wants to grow a really large pumpkin must start with a special seed, a seed that is the offspring of very large pumpkin parents.
STEM Extension:
Students use technology to grow a virtual pumpkin that weighs at least 500 pounds. They apply their understanding of selection, variation, inheritance, and the needs of plants to optimize the growth of large pumpkins over many generations.
NGSS Standards:
Grade 1, LS3-1. Make observations to construct an evidence-based account that young plants and animals are like, but not exactly like, their parents.
Grade 3, LS1-1. Develop models to describe that organisms have unique and diverse life cycles but all have in common birth, growth, reproduction, and death.
Grade 3, LS3-1. Analyze and interpret data to provide evidence that plants and animals have traits inherited from parents and that variation of these traits exists in a group of similar organisms.
Grade 3, LS3-2. Use evidence to support the explanation that traits can be influenced by the environment.
Utah Standards:
Grade 1. Communicate observations about the similarities and differences between offspring and between populations.
Grade 1. Observe how living things change. Describe and model life cycles of living things.
Grade 5. Compare various examples of offspring that do not initially resemble the parent organism but mature to become similar to the parent organism.
Grade 5. Using supporting evidence, show that traits are transferred from a parent organism to its offspring.
Grade 5. Contrast inherited traits with traits and behaviors that are not inherited but may be learned or induced by environmental factors.
Teaching materials:
Computer model: Pumpkin Contest (Identify the model on the directed page and click on "download simulation".
Recommended Teaching Sequence:
Day 1: Students measure the size and weight of a variety of pumpkins to observe the variation of traits. Students begin to investigate how different amounts of water affect plant growth. (Core Idea= Variation of Traits)
Day 2: Students observe seeds inside a pumpkin and a decaying jack-o-lantern. Students develop a model of the pumpkin life cycle. (Core Idea= Reproduction)
Day 3: Students sort a variety of seeds and observe the variation of traits. Students measure the size and weight of a pumpkin family, the offspring of a single mini pumpkin. (Core Idea= Inheritance of Traits)
Day 4: Students observe the seeds or plants growing in different amounts of water and record observations in science notebooks. Students read to obtain information about how a farmer grows such a large pumpkin. Students develop the rules for a computer model that would allow them to grow a virtual pumpkin patch over many generations. (Core Idea= Selection)
Day 5: Students use a computer model of a pumpkin patch to collect data on the weight of pumpkins over six generations, with and without selection. Students graph the results of their experiment.
Day 6: Students use a computer model of a pumpkin patch to collect data on the weight of pumpkins over six generations, with more or less water and fertilizer. Students graph the results of their experiment.
Day 7: Students are challenged to use the computer model of a pumpkin patch to grow a pumpkin that weighs at least 500 pounds in less than 30 years. Students construct a written explanation based on evidence for how a farmer grows such a large pumpkin.
Formative Assessment:
Use what students have written in their science notebooks as a formative assessment, including model of pumpkin life cycle, charts comparing variation of traits, data collected from the computer model, graphs, and written explanation for the phenomenon of a 2,000 pound pumpkin.
Do students understand that variation is observed in families and in populations of organisms? Do students understand that offspring inherit traits from their parents? Do students understand that selection can be used to change the traits in a population of organisms over many generations?
Lesson Contributors:
April Mitchell, Science Specialist, Salt Lake City School District
Lin Xiang, Assistant Professor of Science Education, University of Kentucky