Digestive System Activity: 8 Hands-On Stations for Teaching Mechanical Digestion, Chemical Digestion, and the Journey of Food (TEKS 7.13A)

Chris Kesler · 8 min read

Hand a 7th grader a banana, a saltine, a Ziploc bag, and 15 drops of vinegar. Tell them to mash it, seal it, and squeeze it into their stomach. Twenty seconds later, the bag is a brown soup that doesn't look like food anymore. That's the moment they actually understand what their stomach does. Until then, "the stomach digests food" is just a sentence.

The Digestive System is the system kids think is simple because they eat every day. They know food goes in one end and waste comes out the other. They've heard "stomach" and "intestines" since elementary school. But ask them what saliva does, what enzymes are, where mechanical digestion stops and chemical digestion starts, or which organ makes bile, and the surface knowledge falls apart fast.

The Digestive System Functions Station Lab for TEKS 7.13A closes that gap in one to two class periods. Kids run a hands-on simulation of the mouth and stomach with a sealed bag of food, study reference cards covering 8 different digestive organs (mouth, salivary gland, pharynx, esophagus, stomach, small intestine, pancreas, liver, gallbladder, large intestine), build a timeline of food's journey through the body, and learn the difference between mechanical and chemical digestion. By the end, they can trace a piece of pizza from the mouth all the way to the large intestine and explain what each organ does along the way.

⏱ 1–2 class periods 📓 7th Grade Science 🧪 TEKS 7.13A 🎯 Built-in differentiation 💻 Print or Digital

8 hands-on stations for teaching the digestive system

A station lab is a student-led activity where small groups rotate through 8 stations (plus a 9th challenge station for early finishers) at their own pace during one to two class periods. You become a facilitator instead of a lecturer. You walk around, spot-check the bag-stomach simulations, and break misconceptions while kids work through the rotation.

The Digestive System Functions Station Lab has four input stations (where students take in new info on mechanical digestion, chemical digestion, enzymes, and the path food takes through 8 different organs) and four output stations (where they show what they learned). Here's what's at each one.

📷 Image slot 1 — add screenshot

📷 Image slot 2 — add screenshot

4 input stations: how students learn the digestive system

🎬 Watch It! —

A short YouTube video walks students through the journey of food from mouth to large intestine. Three questions follow: describe the journey of food and name the organs that help digest it, how does saliva help in the digestive process, and if nutrients are not absorbed by the small intestine, where do they move next. Visual learners come alive at this station before they ever pick up a Ziploc bag.

📖 Read It! —

A one-page passage called "Breaking Down Digestion" introduces the digestive system as the process that turns food into nutrients the body can use. Students learn the difference between mechanical digestion (chewing in the mouth) and chemical digestion (saliva, stomach acid, enzymes), and how the liver and pancreas help out. Three multiple-choice questions follow plus five vocabulary words to define: digestive system, stomach, mechanical digestion, chemical digestion, enzyme. Comes in two reading levels (Dependent and Modified) plus a Spanish version.

🔬 Explore It! —

This is the heart of the lab. Students build a model of digestion using a Ziploc bag, a piece of banana, a cracker, water, and 15 drops of vinegar. Step 1: place the banana and cracker into the bag with 3 drops of water. Step 2: seal it and use their hands to mix until there are no clumps (this models the mouth and mechanical digestion). Step 3: squeeze the food to one area and add 15 drops of vinegar (this models the stomach and chemical digestion). Step 4: mix again with their hands until smooth, then examine the contents. Three reflection questions wrap it up: explain how the function of the mouth is modeled, what does the vinegar represent, and where does the mixture go next.

💻 Research It! —

Students examine 11 reference cards: a vitamins-in-food chart, an explanation of common digestive problems (acid reflux and IBS), and organ-function tables for the mouth, salivary gland, stomach, small intestine, pharynx, esophagus, pancreas, large intestine, liver, and gallbladder. A separate card explains chemical digestion as the process where food is broken down by enzymes in the mouth, stomach, and intestines. Six questions check whether they can identify which organs play a role in chemical digestion, which produce digestive materials, which transports food from mouth to stomach, which begins digestion by chewing, how chemical digestion helps the body use food for energy, and what two problems are associated with the digestive system.

📷 Featured station deep-dive — add screenshot of the Explore It! task card

4 output stations: how students show what they learned

📋 Organize It! —

A two-column card sort. Kids match each organ (mouth, esophagus, stomach, small intestine, large intestine) with its description. "Starts the digestive process by chewing the food we eat" → mouth. "Uses enzymes to break food down into nutrients the body can use" → small intestine. Easy to spot-check at a glance.

🎨 Illustrate It! —

Students draw a timeline of food moving through the digestive system. Each stop on the timeline gets a caption describing what is happening: esophagus, liver, lower intestine, mouth, pancreas, small intestine, and stomach. Even kids who say "I can't draw" surprise themselves here. The timeline locks in the order of digestion that's easy to mix up when you're just reading about it.

✍️ Write It! —

Three open-ended questions: how does the digestive system transform food into nutrients and energy, why is the small intestine an important part of the digestive process, and what are the four main components of the digestive system and how do they work together. The third question is the killer. It forces kids to chain together everything from the lab into one continuous explanation.

📝 Assess It! —

Three multiple-choice questions plus a fill-in-the-paragraph that uses all five Read It! vocabulary words (digestive system, stomach, mechanical digestion, chemical digestion, enzyme). The paragraph reads: "The ___ breaks food down into molecules and nutrients the body can use. ___ begins in the mouth when we chew. ___ occurs in the mouth through saliva and continues in the ___..." If you're grading the lab, this is the easiest station to grade.

Bonus Challenge It! station for early finishers

🏆 Challenge It! —

Four optional extensions: create trading cards for the mouth, stomach, and small intestine that explain each organ's role and importance, run an imaginative interview with food after it passes through your mouth into your stomach, design a graphic organizer comparing mechanical and chemical digestion (with the organs responsible for each), or rewrite a nursery rhyme to explain the journey of food through the digestive system. Requires teacher approval before they start.

How this fits into a complete digestive system unit

This Station Lab is the Explore day of our full Digestive System Functions Complete 5E Lesson for TEKS 7.13A. The complete two-week unit follows the 5E method of instruction and includes an Engage hook, the Digestive System Station Lab for Explore, PowerPoint slides and interactive notebook pages for Explain, student choice projects to Elaborate, and an Evaluate assessment.

Most teachers grab the full 5E because the Station Lab lands hardest with the days around it. But if you just need a strong hands-on day on the digestive system, the Station Lab on its own does the job.

Two options

Full 5E Lesson $13.20 Get the 5E Lesson

Just the Station Lab $7.20 Get the Station Lab

Materials needed to teach the digestive system

Materials beyond what's in the download:

Small Ziploc bags — one per group rotation for the bag-stomach simulation.
Banana — about 1 small slice per group. Bruised or overripe is fine.
Saltine crackers — one cracker per group rotation.
White vinegar with a dropper — about 15 drops per group (small bottle is plenty).
Water with a dropper — about 3 drops per group.
Index cards for the Challenge It! trading-cards extension.
Colored pencils or markers for the Illustrate It! station timeline.
Pencils and the printed answer sheets (included)
A device with internet for the Watch It! station
Paper towels for the Explore It! cleanup (squishy bags happen)

Standard covered: Texas TEKS 7.13A —

Investigate and explain the functions of the circulatory, respiratory, digestive, urinary, immune, integumentary, nervous, muscular, skeletal, reproductive, and endocrine systems. Supporting Standard.

See the full standard breakdown →

Grade level: 7th grade life science

Time: One to two class periods (45–110 minutes total). Plan for two periods the first time you run a station lab.

Common student misconceptions this lab fixes

"Digestion only happens in the stomach."
Kids hear "the stomach digests food" so often they believe digestion is one event in one place. The Read It! passage and the Research It! cards make it clear that digestion is a chain that starts in the mouth (mechanical digestion through chewing, plus chemical digestion through saliva and amylase), continues in the stomach (with stomach acid), and finishes in the small intestine (with enzymes from the pancreas and bile from the liver and gallbladder). The Explore It! bag simulation reinforces this: students start with whole banana and cracker (mouth), squeeze it to one spot, then add vinegar to model the stomach acid. Two stages, one mixture, all happening to the same food.
"Mechanical and chemical digestion are completely separate processes."
Kids assume mechanical digestion happens first (in the mouth) and chemical digestion happens later (in the stomach). The Read It! passage corrects this directly: chemical digestion also starts in the mouth when saliva mixes with food. The Research It! card on chemical digestion names the three places it happens: mouth, stomach, and intestines. The Explore It! simulation models both at the same time. Hands mashing the banana = mechanical. Adding vinegar = chemical. They're happening in parallel, not in sequence.
"The large intestine is just where waste sits before leaving the body."
Kids treat the large intestine as a holding tank. The Research It! card on the large intestine names two jobs: re-absorbs water and nutrients, AND stores waste prior to removing it. That first job is the one most kids don't know about. The Read It! passage spells it out: "the large intestine, where water is absorbed, and the waste remains until your body removes it." The Organize It! card sort drives it home with the description "absorbs water and nutrients that the small intestine does not." The large intestine is doing useful work right up until the very end of the chain.

What you get with this digestive system activity

📷 Inside-the-product — add screenshot of Read It passage or sample answer sheet

When you buy the Station Lab, you get a single download with everything you need:

Print version at two reading levels (Dependent for on-grade, Modified for additional support) plus a Spanish Read It! passage
Digital version as PowerPoint files (works in Google Slides too) at both levels — for 1:1 classrooms or Google Classroom
Teacher Directions and Answer Key for both versions, all keys included
Station task cards ready to print, laminate, and drop in baskets at each station
Reference cards for the Research It! station (organ-function tables for mouth, salivary gland, stomach, small intestine, pharynx, esophagus, pancreas, large intestine, liver, gallbladder; vitamins-in-food chart; chemical digestion explanation; digestive problems card)
Sort cards for the Organize It! station (10 cards matching each organ to its description)
Student answer sheets for each level

No login required. Download once, use forever. Reprint as many times as you want.

Tips for teaching the digestive system in your 7th grade classroom

Two things make this lab go smoother the first time:

1. Pre-prep the Explore It! supplies in small cups so the bag station moves fast.

If kids have to peel bananas, count out crackers, and figure out the dropper at the station, you lose 7 minutes per group. Set up small Dixie cups ahead of time: one cup with a banana slice and one cracker per group, plus a small bottle of vinegar with a dropper and a small bottle of water with a dropper. Drop a few paper towels at the station too. Some kids will squeeze too hard and pop the bag. Build that into your plan.

2. Have students chew a saltine slowly before they start the lab.

Before kids hit the rotation, give every student one saltine and tell them to chew it slowly for 30 seconds without swallowing. Around the 20-second mark, the cracker starts tasting sweet. That's the salivary amylase in their mouth breaking the starch down into sugar. It's a 60-second formative assessment that proves chemical digestion starts in the mouth, ties straight into the Read It! passage, and primes them for the bag-stomach simulation in Explore It!

Get this digestive system activity

Digestive System Functions Station Lab for 7th grade life science — TEKS 7.13A

Buy the Station Lab — $7.20

Or if you want the full two-week experience with the Engage hook, Explain day, Elaborate extension, and Evaluate assessment all included:

Buy the full 5E Complete Lesson — $13.20

(Station Lab is included)

Frequently asked questions

What does TEKS 7.13A cover?

Texas TEKS 7.13A asks 7th grade students to investigate and explain the functions of all the major body systems, including the digestive system. By the end, students should be able to describe how the digestive system breaks food down into nutrients, distinguish between mechanical and chemical digestion, name the major digestive organs and what each one does, and trace the path of food through the body. This Station Lab focuses specifically on the digestive system. The other body systems (circulatory, respiratory, urinary, immune, integumentary, nervous, muscular, skeletal, reproductive, endocrine) each have their own dedicated Station Lab.

What's the difference between mechanical and chemical digestion?

Mechanical digestion is the physical breakdown of food into smaller pieces. Chewing in the mouth is the most obvious example, but the churning action of the stomach is also mechanical. Chemical digestion is the breakdown of food at the molecular level using enzymes and acids. It starts in the mouth (saliva contains amylase, an enzyme that begins breaking down starch), continues in the stomach (with stomach acid and protein-digesting enzymes), and finishes in the small intestine (with enzymes from the pancreas and bile from the liver and gallbladder). The Explore It! bag simulation models both at the same time: hands mashing the food represent mechanical digestion, and the vinegar represents the chemical digestion of stomach acid.

How long does this digestive system activity take?

One to two class periods (45 to 110 minutes total). The Explore It! bag-simulation station is the longest part, so plan for two periods the first time you run a station lab. Once your class has the routine down, most groups can finish all 8 stations in one period.

Do I need to provide my own materials?

Small Ziploc bags, banana slices, saltine crackers, white vinegar with a dropper, water with a dropper, index cards, and colored pencils. Total cost for a class of 30: under $10 if you don't already have these supplies. The Watch It! station also needs a device with internet.

Can I use this in a 1:1 digital classroom?

Yes. The full digital version (PowerPoint or Google Slides) works in 1:1 classrooms and Google Classroom. The bag-simulation activity can be replaced by an interactive drag-and-drop version in the digital file, or you can keep the Explore It! station as the one physical center kids rotate through.