1. Prior to this activity, cut out one set of the Got Guts? Descriptions for the cow and pig. Draw a large outline of either a cow or a pig on a piece of foam board for each group.
2. Project the Animal Appetites handout onto a screen. Read the story aloud. Solicit student responses to the included questions.
3. Tell students that they are going to act as animal nutritionists. Animal nutritionists must have an extensive knowledge of how animals digest food. They use their knowledge to formulate diets for animals. The diets they create must be nutritionally sound, good-tasting, and economical for the ages and types of animals that will use them.
4. Introduce the term digestive tract. Briefly review the human digestive system and the roles of teeth and the mouth, esophagus, stomach, small intestine, large intestine, and colon in the function of digesting food. Allow students to identify the parts they know, and if possible, the related function. Highlight the following features:
   • Digestion begins in the mouth. As the teeth tear and chop food, saliva moistens it for easy swallowing.
   • From the throat, food travels down a muscular tube in the chest called the esophagus. Waves of muscle contractions force food down through the esophagus to the stomach.
   • The stomach muscles churn and mix the food with acids and enzymes, breaking it into smaller, more digestible pieces.
   • Digestion continues in the small intestine, a tube-like structure that absorbs nutrients into the bloodstream.
   • The large intestine’s main function is to remove water and minerals from the undigested matter and form solid waste that can be excreted.
   • The colon is part of the large intestine. Bacteria in the colon help to digest the remaining food products.
5. Tell students that they will use household materials to construct models of both monogastric and ruminant digestive systems. Divide the class into groups of five students. Assign each group a cow or pig digestive tract.
6. Give each group the Pig Digestive Tract or Cow Digestive Tract handout. Distribute foam board, modeling materials (including balloons, tubes, hoses, straws, string, rope, and empty soft drink bottles, chenille stems, milk jugs, and food containers), and corresponding Got Guts? Labels for the cow and pig.
7. Instruct students to research their assigned animal, using classroom and Web resources, and then create a model of the animal’s digestive tract on the foam board using the labels and materials provided.
8. Once students have completed their models, display them around the room. Gather students in a location where both cow and pig digestive tracts are visible. Distribute the Got Guts? Descriptions (both pig and cow) to students. Lead students in a review of each digestive tract, using the Got Guts? Teacher Review as needed. Throughout the review, have students place the correct description of each organ on the correct model.
9. Summarize student learning with a classroom discussion. Include the following points in the discussion:
   • Monogastric and ruminant digestive systems are different. Monogastric systems have one true stomach, while ruminants have a multi-chambered stomach.
   • Animals prefer foods that can be easily digested and used by their body. Cattle have ruminant digestive tracts with large microbial populations that allow them to eat complex plant materials. Pigs and humans have monogastric digestive tracts.
   • Animal nutritionists use their knowledge about animals and their digestive tracts to formulate diets that are nutritionally sound, good-tasting, and economical.
   • The proper nutrition of livestock animals is a key component of a successful production system. Just like humans, animals that consume the nutrients they need will stay healthy and grow stronger.

Variations

• During the Interest Approach — Engagement, solicit student responses using a text message poll such as Poll Everywhere or SMSPoll. Summarize student responses by creating a word cloud.
• Have students choose a livestock animal to research and design a digestive model. Compare the digestive systems of a variety of animals including llamas, sheep, goats, cattle, horses, and pigs.

ELL Adaptations

• Students create a diagram of the selected digestive system before working on model. Graphic organizers are a means of introducing and assessing concepts in a manner that encourages meaningful learning.
• The activities in this lesson employ group work and cooperative learning. These activities provide opportunities for students to exchange, write, and present ideas. Students use a variety of skills that work together to increase understanding and retention.