6th Grade - Unit 4: Reproduction and Heredity

Instructional Sequence

Assessment Types at
This Stage

Assessment Description

Learning Target

Engage

Observations: Accesses students’ background knowledge about how plants reproduce and the nature of the interactions between plants and pollinators.

Students watch a video of an interaction between a bee and a plant with the sound off. Students make predictions about what might be happening and why each organism participates.

Do not introduce the word pollination if students do not use the word. At this point, all explanations for why the bee interacts with the plant are acceptable.

Explore

Explanation: Students explain the nature of the interactions between plants and pollinators.

Making Predictions: Students make predictions based on evidence.

Students use structure and trait information on pollinators and plants to revisit their initial ideas about the nature of the interactions between bees and plants. Students also predict which animals pollinate certain plants and why.

Students should be able to 

• State that certain traits or structures in plants attract pollinators.
• Make connections between animal behaviors and pollination.

Explain

Pair Discussion and Written Responses: Students explain their understanding of plant reproduction.

Students read the article “How Do Plants Reproduce?” Students summarize the ways in which plants reproduce with and without the help of pollinators.

Students should be able to

• Explain how certain plant traits and structures can lead to an increased chance of pollination.

Elaborate

Analyzing Data and Making Connections: Students apply their understanding of pollination to the Culminating Project.

Students consider how the structures of the strawberry flower and pollinators support pollination. Students discuss what would happen if there were no pollinators and the usefulness of having multiple pollinators for a given plant.

Students should be able to 

• Identify structures that, in general, help increase plants’ chances of pollination (e.g., bright flowers, heavy, sticky pollen).
• Explain what would happen if certain pollinators were not available for plants.

Evaluate

Discussion and Critique:

Students evaluate their understanding by critiquing an imaginary student’s statement.

Students revisit their Know, Wonder, Learned charts and the Driving Question Board.

Students read an imaginary student’s explanation of pollination and apply their understanding to critique, correct, and clarify the statement.

Students record what they have learned and identify the questions they have answered from the Driving Question Board.

See Explain and Elaborate.

Instructional Sequence

Assessment Types at
This Stage

Assessment Description

Learning Target

Engage

Observations: Assesses students’ background knowledge about traits, sexual reproduction, and asexual reproduction.

Students look at pictures of  humans and bacteria. Students are asked to note any patterns in the similarities and differences between parents and offspring.

At this point, students should notice that some offspring look identical to their biological parents and some look similar to, but also different from, their biological parents. Students should begin to make predictions about why this is the case, but they do not have to be able to fully understand.

Explore

Making Connections: Students use diagrams, videos, and text to make connections between the type of reproduction and trait variation in offspring. 

Students observe several examples of asexual reproduction and compare that with human reproduction in terms of parent number and trait variation. 

Students should be able to

• Notice that some organisms reproduce with one biological parent and some reproduce with two biological parents. Some students might start to make connections between the type of reproduction and trait variation, but they do not need to build a full explanation at this point.

Explain

Pair Discussion and Written Responses, Creating Models:

Students demonstrate their understanding through the discussion.

Part 1: Students engage in the Protocol to Support Close Reading and answer questions using the Listening Triads protocol for the article “Asexual and Sexual Reproduction.”

Part 2: Students use Punnett squares to model the passing of traits from parents to offspring. 

Students should be able to 

• State that asexual reproduction results in offspring that are identical to their parents in terms of genes and traits.
• Understand that sexual reproduction results in offspring that share half of the genetic information of each biological parent. 
• Explain that due to the fact that genes determine traits, sexual reproduction results in more variation than asexual reproduction.

Elaborate

Making Predictions and Connecting to New Contexts: Students apply their understanding of sexual and asexual reproduction to a historical event.

Students read an article about the benefits and tradeoffs of sexual reproduction versus asexual reproduction and construct a comparison table.

Students should be able to 

• Identify examples of asexual and sexual reproduction.
• Think about environmental scenarios that would favor sexual reproduction over asexual reproduction and vice versa.

Evaluate

Discussion and Written Responses: Students assess their understanding by considering strawberry reproduction and traits.

Students answer questions about strawberry reproduction and traits and consider how this understanding will impact their garden design. 

Students should be able to 

• Explain why variation is important for the ability to withstand change in the environment.

Instructional Sequence

Assessment Types at
This Stage

Assessment Description

Learning Target

Engage

Data Analysis and Predictions 

Students analyze rain data for San Francisco and think about how this factor might affect the growth of flowering plants in the city.

At this point, all ideas are acceptable. Some students might think there is no connection between plants and rainfall and some might make connections to photosynthesis or watering plants in their home.

Explore

Drawing Conclusions from Data Analysis: Students use their experimental data and the case study information provided to create explanations.

Part 1: Students analyze data from their experiments and think about whether environmental factors affected the growth of the plant.

Part 2: Students analyze case study data and determine how an environmental factor affected plant or animal growth.

Students should be able 

to 

• Cite evidence for why they think a particular environmental factor affects plant or animal growth.

Explain

Writing a Lab Report Conclusion Paragraph

Students consider how the case studies might relate to their garden plans. Students use their data and evidence from an article to write a conclusion that explains the effect an environmental factor had on plant growth.

Students should be able to 

• Cite evidence to explain how environmental factors affect organism growth.

Elaborate

Apply Understanding to a New Context: Students apply their understanding of organism growth to the Culminating Project.

Students review their conclusions and make recommendations based on findings from their experiments.

Students should be able to 

• Explain how several environmental factors affect the growth of organisms.

Evaluate

Writing Explanations
 

Students evaluate their understanding by explaining the effect of several environmental changes on an organism’s growth.

Students should be able to 

• Use evidence to predict how strawberries will be similar to and different from their parents or offspring depending on the type of reproduction.
• Use evidence to predict how heredity and the environment will affect the growth of the strawberries. 

Desired Results

Overview

Through investigations, students identify several cause and effect relationships related to reproduction, heredity, behavior, and organism growth. In Subunit 1, students explain how flowering plant structures can increase the chance of pollination. In Subunit 2, students explain how sexual reproduction results in more genetic and trait variation in offspring than asexual reproduction. In Subunit 3, students analyze data from self-designed experiments to determine the effect environmental factors have on the growth of organisms. 

Project Tasks

Connections to Culminating Project Liftoff: Students observe strawberries and design a plant growth experiment.

Connections to Culminating Project Subunit 1: Students are given information about structures of flowering plants and pollinators. Students consider how this could increase the plant’s chance of pollination. Students consider the benefits of multiple methods of pollination.

Connections to Culminating Project Subunit 2: Students consider the connection between genes and strawberry traits as well as the benefits of genetic variation on the survival of strawberries in their garden.

Connections to Culminating Project Subunit 3: Students consider how environmental factors affect the growth of strawberries. Students think about how their experimental data could inform their plans.

Estimated length of project: 280 minutes

ESTABLISHED GOALS

MS-LS3-2. Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation. [Clarification Statement: Emphasis is on using models such as Punnett squares, diagrams, and simulations to describe the cause and effect relationship of gene transmission from parent(s) to offspring and resulting genetic variation.]

MS-LS1-4. Use argument based on empirical evidence and scientific reasoning to support an explanation for how characteristic animal behaviors and specialized plant structures affect the probability of successful reproduction of animals and plants respectively. [Clarification Statement: Examples of behaviors that affect the probability of animal reproduction could include nest building to protect young from cold, herding of animals to protect young from predators, and vocalization of animals and colorful plumage to attract mates for breeding. Examples of animal behaviors that affect the probability of plant reproduction could include transferring pollen or seeds, and creating conditions for seed germination and growth. Examples of plant structures could include bright flowers attracting butterflies that transfer pollen, flower nectar and odors that attract insects that transfer pollen, and hard shells on nuts that squirrels bury.]

MS-LS1-5. Construct a scientific explanation based on evidence for how environmental and genetic factors influence the growth of organisms. [Clarification Statement: Examples of local environmental conditions could include availability of food, light, space, and water. Examples of genetic factors could include large breed cattle and species of grass affecting growth of organisms. Examples of evidence could include drought decreasing plant growth, fertilizer increasing plant growth, different varieties of plant seeds growing at different rates in different conditions, and fish growing larger in large ponds than they do in small ponds.] [Assessment Boundary: Assessment does not include genetic mechanisms, gene regulation, or biochemical processes.]

NGSS Lead States. 2013. Next Generation Science Standards: For States, By States. Washington, DC: The National Academies Press.

ESSENTIAL QUESTION

How can we design a garden that supports the growth and reproduction of strawberry plants?

Students will be able to independently use their learning to.

• Select a plan that ensures the growth and reproduction  of strawberries in a garden.
• Analyze San Francisco weather data and student-designed experiment data to support their choice. 

Students will know 

• Sexual reproduction results in offspring with more genetic and trait variation than asexual reproduction.
• Specialized plant structures and traits increase their chances of pollination.
• Environmental factors influence the growth of organisms. 

Evidence

Assessment Evidence

PERFORMANCE TASK: Creating an argument presentation to support a choice of design plans for a strawberry garden.

• Group Culminating Project
  There are two possible design plans that have been suggested for the new strawberry garden. Design Plan A recommends that the class clone last year’s plants to make the new garden. Design Plan B recommends that the class plant seeds collected from last year’s plants to make the new garden. Each group must decide which plan to select. Each group must also create an argument presentation that explains the reasons that support choosing one plan over the other. 

In student’s argument presentations, they must choose either Plan A or Plan B and support their choice with evidence. Each presentation will have three parts:  
 

1. Part 1: Modeling Asexual and Sexual Reproduction: First students must explain how traits are inherited from the biological parent plants in each plan. To do this, students must develop models for both asexual and sexual reproduction of strawberry plants. Students should use both diagrams and text in their models. Students models must answer the following questions:

• Does this process require another plant?
• Does this process require interactions with other parts of the environment (ex: wind, water, animals)?
• How does the genetic information of the offspring compare to the genetic information of the biological parents?
• How do the traits of the offspring compare to the traits of the biological parents?
• What are the benefits of this method of reproduction?
• What are the drawbacks of this method of reproduction?

2. Part 2: Explain The Choice of Design Plan A or Design Plan B: In this section of the presentation, students must explain why they would choose Plan A or Plan B. In this part of the presentation students must address whether their chosen plan will result in more, less, or the same amount of genetic and trait variation in the strawberries than those of the other plan, and how this affects the choice of design plans. Student arguments must be supported by evidence and need to address the following criteria:

• Criteria 1: How Long the Strawberries Stay Fresh
  • Each design plan has two options for pollination which affects freshness. Students must choose one option and explain the reasons for the choice using evidence. In the explanation, students must describe how the choice can affect the development of the strawberries in the garden. Specifically, students must describe how this choice will affect how long the strawberries will stay fresh.  

• Criteria 2: Flavor of The Strawberries
  • Students must explain how the choice of Design Plan A or Design Plan B is related to the flavor of the strawberries in the new garden. In the selected plan, students must predict whether all of the new strawberries will taste the same or if  different flavors will be possible. Students must explain how this information affects their choice of plans.
• Criteria 3: Environmental Factors That Influence Strawberry Plant Growth  
  • What environmental factors influence the growth of strawberry plants?
  • Students must describe the ideal conditions needed for the garden to be the most successful. 
  • Based on the choice of Design Plan A or Design Plan B, students must predict whether all plants in the garden will be affected by environmental changes in the same way. Students are asked what they might add to their  plan to ensure that all plants can grow successfully in a variety of environmental conditions.

Individual Culminating Project
Individually, students must provide feedback to each group for their argument presentation. Your job is to evaluate each argument presentation and provide each group with suggestions for how groups might improve their selected plans. 

Learning Plan

Subunit 1

In this subunit, students focus on structures that increase the chance of pollination in flowering plants.. 

Subunit 2

In this subunit, students explain how the type of reproduction (sexual or asexual) affects the amount of gene and trait variation in offspring. Note that the Performance Expectation does not ask students to understand the mechanism of how genes code for proteins and how proteins determine traits. 

Subunit 3

In this subunit, students use evidence from an experiment and articles to explain how environmental factors affect the growth of organisms

Unit Map

Reproduction and Heredity

Essential Question: How can we design a garden that supports the growth and reproduction of strawberry plants?

Lift-Off and Introduction to the Culminating Project

Subunit 1: Flowering Plants and Pollinators

What characteristics are important for improving the chance of pollination in flowering plants? Why?

Engage • Explore • Explain • Elaborate • Evaluate

Subunit 2: Traits of Organisms

How does reproduction affect the traits of offspring?

Engage • Explore • Explain • Elaborate • Evaluate

Subunit 3: Organism Growth

How do environmental factors affect the growth and reproduction of flowering plants?

Engage • Explore • Explain • Elaborate • Evaluate

Group Culminating Project

Designing a strawberry garden

Individual Culminating Project

Individual garden plan

Course Concepts

+ Foundational Crosscutting Concepts: These concepts are foundational to the understanding of middle school science. They are present throughout the course. Students are expected to continue to apply their knowledge of the concepts to subsequent relevant projects. 

* Focal Crosscutting Concept: This concept is called out consistently in the Teacher Book and once per subunit in the Student Book. Students will consider the unit project through the lens of this Crosscutting Concept. 

Crosscutting Concept

Unit 1: Energy

Unit 2: Human Impact on Earth’s Climate

Unit 3: Cells and Body Systems

Unit 4: Reproduction and Heredity

Patterns

*

Cause and Effect

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*

+

+

Scale, Proportion, and Quantity

+

+

Systems and System Models

+

+

*

Energy and Matter

*

Structure and Function

+

Stability and Change

+

Science and Engineering Practices 

+ Foundational Science and Engineering Practices: These practices “carry forward” through the course. Students focus on one of them per unit and are then expected to continue to apply that knowledge to subsequent relevant projects. 

* Focal Science and Engineering Practice: This practice is called out consistently in the Teacher Book and once per subunit in the Student Book. Students will use this practice to complete the unit project. 

Science and Engineering 

Practices

Unit 1: Energy

Unit 2: Human Impact on Earth’s Climate

Unit 3: Cells and Body Systems

Unit 4: Reproduction and Heredity

Asking Questions and Defining Problems 

+

+

Developing and Using Models 

*

+

+

+

Planning and Carrying Out Investigations 

+

+

+

Analyzing and Interpreting Data

+

*

Using Mathematics and Computational Thinking

Constructing Explanations and Designing Solutions

+

+

*

Engaging in Argument from Evidence

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*

+

Obtaining, Evaluating, and Communicating Information

+

+

+

MS-LS3-2

Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation. [Clarification Statement: Emphasis is on using models such as Punnett squares, diagrams, and simulations to describe the cause and effect relationship of gene transmission from parent(s) to offspring and resulting genetic variation.]

MS-LS1-4

Use argument based on empirical evidence and scientific reasoning to support an explanation for how characteristic animal behaviors and specialized plant structures affect the probability of successful reproduction of animals and plants respectively. [Clarification Statement: Examples of behaviors that affect the probability of animal reproduction could include nest building to protect young from cold, herding of animals to protect young from predators, and vocalization of animals and colorful plumage to attract mates for breeding. Examples of animal behaviors that affect the probability of plant reproduction could include transferring pollen or seeds, and creating conditions for seed germination and growth. Examples of plant structures could include bright flowers attracting butterflies that transfer pollen, flower nectar and odors that attract insects that transfer pollen, and hard shells on nuts that squirrels bury.]

MS-LS1-5

Construct a scientific explanation based on evidence for how environmental and genetic factors influence the growth of organisms. [Clarification Statement: Examples of local environmental conditions could include availability of food, light, space, and water. Examples of genetic factors could include large breed cattle and species of grass affecting growth of organisms. Examples of evidence could include drought decreasing plant growth, fertilizer increasing plant growth, different varieties of plant seeds growing at different rates in different conditions, and fish growing larger in large ponds than they do in small ponds.] [Assessment Boundary: Assessment does not include genetic mechanisms, gene regulation, or biochemical processes.]

Misconception 

Accurate Concept

Pollination and fertilization are the same thing. 

Pollination is the transfer of pollen from anther to stigma (except in the case of gymnosperms). Fertilization is the combination of pollen and ovule that occurs in the ovary.

Misconception 

Accurate Concept

Only animals have genes; plants, mushrooms, and other organisms do not. 

From American Association for the Advancement of Science (AAAS) Misconceptions (http://assessment.aaas.org/misconceptions/RHM048/300)

All organisms have genes, but some pass on all of their genes to their offspring (asexual reproduction) and some only pass on half of their genes to their offspring (sexual reproduction).

If the offspring looks more like one parent, it must have gotten more genetic information from that parent. 

Related:

Each parent contributes genetic information for certain characteristics and not others (e.g., a child has his father’s nose and his mother’s eyes).

From AAAS Misconceptions (http://assessment.aaas.org/misconceptions/RHM033/302)

Sexual reproduction involves two biological parents. The cells that make up plants and animals that reproduce sexually contain two versions of each gene called alleles. Before sexual reproduction can happen, each biological parent has to produce sex cells. Sex cells only have one allele for each trait. During fertilization, the female and male sex cells combine (see the fertilization diagram). For each gene, an offspring receives one allele from the female sex cell and another from the male sex cell. Which allele is passed to the offspring is random. The alleles may be the same or different. This means that each offspring receives a unique set of alleles. Sexual reproduction produces offspring with more genetic variation than asexual reproduction. This is why different offspring of the same two biological parents can look different from each other. 

Misconception 

Accurate Concept

Only genetic factors or only environmental factors affect an organism’s growth.

Genetic factors as well as local conditions affect the growth of organisms.

Permanent

Consumable

Teacher Provided

• Magnifying lens (8)
• Soil thermometer (8)
• Digital moisture meter (8)
• Water mister (8)
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• Measuring cups (16)
• Full-spectrum bulb (8)

• 5 oz plastic cups, 100 count pack (1)
• Soil (1 bag)
• Green bean seeds (48)
• pH paper (40)

• Piece of chart paper (11)
• Large 5"x7" sticky notes (144) 
• Sticky notes (144) 
• Highlighters (32)
• Marker (32) 
• Meter stick (1)
• Rulers (8)
• Plant cutting (1)