Relevancy and Engagement
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Sheep See, Sheep Do (Grades 6-8)
Grade Level
Purpose
Students explore the difference between inherited and acquired traits and understand why knowledge of inherited and acquired traits is important to agriculture. Activities in this lesson include trait sorting, two video clips, a PTC taste test, and student presentations. Grades 6-8
Estimated Time
Materials Needed
Engage:
- Sticky notes, 1 per student
Activity 1: Traits
- AITC Inherited vs. Acquired Kahoot! game
- Personal devices for students to play
- Projector/computer combination
- Alternative Activity:
- Traits List, cut apart and laminated
- Two baskets, one labeled “Inherited” and one labeled “Acquired”
- Alternative Activity:
- Lamb Eats What Mom Eats video
- PTC testing strips, available from most science supply companies
- Hard candies
Activity 2: Value of Domesticated Animals
- Guns, Germs, and Steel video clip
Activity 3: Student Presentations
- Farm Animal Prompt Cards, cut apart, 1 per student or group of students
- Presentation Rubric, 1 per student
Vocabulary
domesticate: to breed a population of animals or plants to serve the purposes of human beings and to need and accept human care
inherited trait: a genetically determined characteristic or quality that distinguishes someone or something; inherited traits are passed in DNA from parents to their offspring
selective breeding: process by which humans control the breeding of plants or animals in order to exhibit or eliminate a particular characteristic
temperament: the usual attitude, mood, or behavior of a person or animal
trait: observable, physical characteristic obtained through genetic inheritance
Did You Know?
- More than 50 breeds of sheep are raised in the United States.1
- As of January 2015, there were more than 5.2 million sheep in the United States.1
- Sheep eat a wide range of plants and can work like self-propelled lawnmowers to control weeds. They are even being used by ski resorts to keep slopes clear of brush and weeds in the summer.1
Background Agricultural Connections
My lamb is black, and he likes to eat Russian olive twigs just like his mother taught him. One of these traits is inherited and one is acquired. Can you guess which is which? Acquired traits develop during the lifetime of the organism but are not in the organism’s DNA and are not inherited by its offspring. Inherited traits are genetically determined. A lamb learning to eat and prefer Russian olive twigs is an example of an acquired trait, and black wool is an inherited trait.
Animals acquire traits by learning from consequences and taking cues from their mothers or caretakers. Notably, mothers of many species teach their offspring about nutrition. Mothers teach their offspring what to eat, how to eat, and where to find food. In addition to learning, traits can also be acquired in response to environmental factors. An animal that has the genetic makeup to grow big and strong may be small and weak if it doesn’t get the nutrition it needs. Similarly, a plant that has the genetic makeup to grow short and stout may be tall and spindly if it sprouts in a place with insufficient sunlight.
All organisms inherit and acquire traits, and this has important implications for farmers who grow plants and raise animals. Throughout history, many animals and plants have been domesticated, or selectively bred to exhibit and pass on certain inherited traits that make them easier for people to raise. After domestication, further selective breeding is often used to continue to improve the productivity and ease of managing agricultural plants and animals. Cows, tomatoes, corn, and strawberries are just a few examples of living things that have been selectively bred by humans for food. The inheritable traits that breeders select in plants and animals may be visible, like fruit or hair color, size, and body shape, or they may be invisible, like health characteristics and temperament.
In addition to breeding for desirable inherited traits, farmers also manipulate the environment and interact with plants and animals to develop desirable acquired traits. For example, fruit trees are staked to make them grow straight and pruned to grow an open canopy. Grapes are trained to grow on the supports provided to hold them off the ground. Dairy cows are given grain in the milk parlor to help them learn to come in and stand to be milked. Calves and lambs are taught that they can get milk by sucking on a bottle. Dogs and horses are trained to work with people, and they are also bred for traits that make them good workers. Often, the best farmers start with plants and animals that have good genetics (inherited traits) and then work hard to ensure that their plants and animals acquire traits that make them productive and easy to work with.
Engage
- Provide each student with a sticky note. Ask students to write their names in the middle of the sticky note.
- Draw a large table on the board with two columns. Title one column "Like what friends and family like" and the other "Just born that way."
- Ask students to place their sticky notes under the statement that they most agree with in response to the following poll question: “What determines the type of ice cream that you prefer; do you like what your friends and family like, or were you just born that way?”
- Lead a short, open-ended discussion on the poll results. Ask students why they answered as they did. Tell them that you will return to this poll question after learning more about inherited and acquired traits.
Explore and Explain
Activity 1: Traits
- Explain to your students the difference between an inherited and an acquired trait.
- Provide each student with a personal device such as a laptop, tablet, or smartphone, and use the AITC Inherited vs. Acquired Kahoot! game to help students practice identifying the difference between inherited and acquired traits. If you do not have enough devices for each student, they may play as teams, or you may use the alternative activity described below.
- Alternative Activity:
- Pass out one trait from the Traits List to each student.
- Using two baskets that you have labeled “Inherited” and “Acquired,” ask students to place their trait statement into the correct basket as you walk down the aisle or to their tables.
- Once all the traits are placed in the baskets, read each trait card in each basket and discuss the accuracy of the trait placement with the students. If any traits are in the wrong basket, switch the trait’s location and help students understand why the trait fits in the other basket.
- Alternative Activity:
- Show students the Lambs Eat What Mom Eats movie. Ask students to explain what they saw. Did these lambs inherit or acquire their taste preferences?
- Next, hold a taste test using PTC testing strips to see which students can taste a bitter flavor. PTC can either be very bitter or virtually tasteless depending on the taster’s genetic makeup. The ability to taste PTC is a trait that roughly 70% of Americans inherit. Have some hard candy available for those who can taste the bitter PTC to help them get rid of the unpleasant taste.
- Refer the students back to the poll question about ice cream preferences. Ask if they would change their answers after watching the movie and doing the PTC taste test, and allow them to move their sticky notes. If students don’t already conclude that some traits can be both inherited and acquired, help them think about the example of taste preference. The ability to taste PTC is inherited, but the movie Lambs Eat What Mom Eats showed that taste can also be acquired through learning.
Activity 2: Value of Domesticated Animals
- Discuss with students how knowledge of inherited and acquired traits is important to agriculture. Explain the meaning of the term domesticate.
- Ask students to help you make a list of domestic farm animals on the board. Your list could include cattle, horses, sheep, goats, chickens, turkeys, or any other domestic animal commonly found on a farm.
- Next, ask students what purpose each of these animals has. Help students recognize that cattle provide meat and milk, horses historically provided transportation and power, sheep provide meat, wool, and sometimes milk, goats provide meat and milk, chickens provide meat and eggs, and turkeys provide meat.
- Point out that each animal’s ancestors were once wild. Long ago humans began hunting wild animals. Recognizing that these animals could benefit their families by providing food to eat and fiber or leather for clothing and tools, humans began domesticating animals about 10,000 years ago. Over the ensuing years, farmers have repeatedly chosen to breed animals with the best characteristics for their needs. The animals that produced the most milk or the finest wool were kept for breeding, while others might have been sold or traded or used for meat. As a result of this selective breeding, farm animals have changed in behavior and appearance over the years.
- While referencing your list of farm animals on the board from steps one and two, ask your students why more animal species are not raised on farms.
- Allow students to begin thinking about this question, then show the first four minutes of Guns, Germs, and Steel (Part 5).
- Consider the following questions for class discussion during or after the video clip:
- Why haven’t most animal species been farmed? (they don’t have a practical use to humans, they could be impractical to farm due to space or diet requirements)
- What type of animals are best suited for farming? (large, plant-eating mammals)
- Why aren’t elephants farmed in Asia to accomplish work? (it takes too long for the animal to reach a mature age for working and for reproduction)
- Why is temperament important to a domesticated animal? (safety and ability to get along with humans)
- What inherited traits and acquired traits make an animal suitable for domestication? (a good temperament to get along with humans, a practical use/benefit to humans such as the ability to perform work or to provide food)
Activity 3: Student Presentations
- Assign each student or group of students a domestic farm animal by giving them one of the attached Farm Animal Prompt Cards.
- Provide students the Presentation Rubric. Ask them to create a short presentation about their animal and to include a visual support. This may be a poster or a PowerPoint, or you may choose to have the students use a multimedia tool like Padlet.
- Instruct students to include the following items in their presentation:
- Explanation of why this animal is suited to domestication
- Name and pictures of assigned farm animal breed
- Purpose of this breed
- Examples of inherited traits that help this breed fulfill its purpose. Note: The prompt cards give students three examples of traits for each animal. To challenge your students, require them to find additional traits through their own research.
- Have the students present their videos and posters to the class and/or post them to your classroom blog or website.
Evaluate
After conducting these activities, review and summarize the following key concepts:
- Farmers use knowledge of acquired and inherited traits to improve the productivity and ease of managing the plants and animals they raise.
- Acquired traits develop during the lifetime of the organism but are not in the organism’s DNA.
- Inherited traits are genetically determined and passed from parents to offspring.