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Free scope and sequences, TEKS breakdowns, phenomenon ideas, and engagement activities for the 2024 Texas science standards.

I'm Chris Kesler, a former award-winning Texas middle school science teacher. This is the site I wish I'd had in the classroom. One hub with TEKS breakdowns, scope and sequences, phenomenon starters, engagement ideas, and resources, all aligned to the standards you actually teach.

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7th Grade TEKS Standards

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TEKS S.7.13D • Organisms & Environments

Natural & Artificial Selection

The Standard

"Describe and give examples of how natural and artificial selection change the occurrence of traits in a population over generations."

💡 What This Standard Actually Means

The Key Verb

"Describe and give examples". Students are describing both natural selection and artificial selection and giving examples of how each one changes the occurrence of traits in a population over generations. The wording here is slightly trimmed from the old standard, but the core ideas are the same. Kids need real examples (peppered moths, Darwin's finches, dog breeds, modern corn) and they need to be able to track how a trait becomes more or less common over time. Instruction can take many forms, such as bean-sorting natural selection simulations, dog breed evolution research, peppered moth case studies, and side-by-side artificial selection timelines for crops.

Natural selection happens when something in the environment (a predator, a disease, a climate shift, a food source) gives some members of a population an advantage. Individuals with traits that help them survive in that environment are more likely to live long enough to reproduce. Their offspring inherit those helpful traits. Over many generations, the population shifts in the direction of those traits. Charles Darwin worked this out while studying finches in the Galápagos. Peppered moths in industrial England are another classic example: when tree trunks darkened with soot, darker moths survived predator attacks more often and became more common in the population.

Artificial selection is the same basic idea, but humans choose the traits instead of the environment. Every breed of dog, from Chihuahuas to Great Danes, came from selective breeding by humans over many generations. Corn, wheat, and broccoli all look dramatically different from their wild ancestors because farmers picked plants with desirable traits and replanted their seeds. Chickens that lay more eggs, cows that produce more milk, apples that resist certain diseases. All artificial selection.

The most important piece for students to understand is that selection acts on populations over generations, not on individual organisms during a single lifetime. A giraffe does not stretch its own neck and pass the longer neck on to its kids. The variation was already there. Giraffes with genes for longer necks happened to reach more food, survive better, and have more offspring. Over generations, the population shifted. Same thing for both natural and artificial selection.

💬 From Chris's Classroom

I'd start this unit with a photo of a Chihuahua next to a photo of a Great Dane and ask the class, "Same species. How?" The answers came flying. "People bred them." "They chose small dogs to breed with other small dogs." That gave me my bridge from a concept they already knew (breeding pets) to the bigger idea (populations change over generations when certain traits get selected). Once they had artificial selection down, I'd flip to Darwin's finches and ask, "If no human was picking, who was doing the selecting here?" That's where natural selection landed, and it never felt as strange to them as when I used to lead with the Galápagos first. Start with dogs. Then move to finches.

⚠️ Misconceptions Your Students May Have

These are some of the most common misconceptions. Knowing what to look for can help you get ahead of them.

"Giraffes stretched their necks to reach higher leaves and passed that on"

✓

This is a Lamarckian misconception. Individual organisms don't change their own traits during their lifetime and pass them to offspring. The variation in neck length was already present in the giraffe population. Giraffes with longer necks happened to reach more food, survive better, and have more offspring. Over generations, longer necks became more common. The selection acts across generations, not within one animal's lifetime.

"Natural selection means the strongest survives"

✓

"Strongest" is the wrong filter. What matters is which traits help an organism survive and reproduce in its specific environment. In some environments, camouflage wins. In others, it's speed. In others, it's the ability to go without water. A polar bear would not survive in the desert. Survival is about fit to the environment, not raw strength.

"Artificial selection and natural selection are totally different"

✓

They use the same mechanism. Some members of a population have traits, those traits get passed on, and over generations the population shifts. The only difference is who or what is doing the selecting. In natural selection, the environment is the filter. In artificial selection, humans are the filter. Students should walk away seeing them as the same process with different selectors.

"Natural selection has a goal or direction"

✓

Natural selection doesn't plan ahead. There's no finish line a species is moving toward. The process just responds to the current environment. If the environment changes, a trait that used to be favorable might stop being favorable, and the population can shift in a different direction. Nature isn't trying to perfect an organism. It's just filtering.

📓 Teaching Resources for 7.13D

These resources are aligned to this standard.

Complete 5E Lesson

Natural & Artificial Selection Complete Science Lesson

The full unit for 7.13D: differentiated station labs, editable presentations, interactive notebooks (English + Spanish), student-choice projects, and assessments. Built on the 5E model.

⏱ Best for: Full unit coverage • Multiple class periods

Station Lab

Natural & Artificial Selection Station Lab

9-station hands-on lab on how natural and artificial selection change populations over generations. Print and digital. English and Spanish.

🔬 Best for: Core instruction • 1-2 class periods

Student Choice Projects

Natural & Artificial Selection Student Choice Projects

Choice board with nine project options plus a "design your own" pathway. Students demonstrate their understanding of selection through writing, building, illustrating, presenting, or digital formats.

🎓 Best for: Project-based assessment • 2-3 class periods

🌎 Phenomenon Ideas for 7.13D

Use these real-world phenomena to anchor your lesson. Show students the phenomenon first, let them wonder, then build toward Natural & Artificial Selection as the explanation.

🔎

Phenomenon 1

Every Breed of Dog Came From Wolves

Show photos of a Great Dane, a Chihuahua, a Bulldog, a Poodle, and a Border Collie. All of them trace back to wolves. Humans selected wolves with traits they wanted (tameness, size, coat, herding behavior) and bred those individuals together over many generations. Over thousands of years, the process created hundreds of dog breeds that look almost nothing like the ancestor.

💬 Discussion Prompt

"If every modern dog came from wolves, how did humans end up with so many different breeds? Why did the process take generations instead of happening all at once?"

🔎

Phenomenon 2

Peppered Moths in Industrial England

In the 1800s, most peppered moths in England were light-colored, which hid them well on light-colored tree bark. When industrial pollution darkened many tree trunks with soot, dark-colored moths were suddenly harder for birds to spot and the lighter moths became easier prey. Over several decades, the dark form of the moth became much more common in industrial areas. After pollution was reduced, the population shifted back toward the lighter form in many places.

💬 Discussion Prompt

"What was doing the selecting in this case? Why did one color of moth become more common and then less common again over time?"

🔎

Phenomenon 3

Broccoli, Cauliflower, Cabbage, and Kale Are the Same Species

Broccoli, cauliflower, cabbage, kale, Brussels sprouts, and kohlrabi all descend from the same wild plant species (Brassica oleracea). Farmers selected for different traits over many generations. They picked for big flower heads (broccoli, cauliflower), tight leafy heads (cabbage), large leaves (kale), small side buds (Brussels sprouts), and swollen stems (kohlrabi). Same starting species, different human choices, dramatically different vegetables.

💬 Discussion Prompt

"How can one plant species turn into six different-looking crops? What does this tell us about how powerful artificial selection can be when it's repeated across many generations?"

💡 Free Engagement Ideas for 7.13D

Bean Predator Simulation

Scatter a mix of colored beans on different fabric backgrounds (green, brown, speckled). Give students 15 seconds to act as a "bird" and pick up as many beans as they can. Count what's left on each background. The beans that survive are the ones best camouflaged. Repeat for a second generation using only the survivors. Populations shift in front of their eyes.

Materials: Dried beans in multiple colors, scraps of fabric, tweezers or spoons, timer

Dog Breed Detective

Give groups five photos of different dog breeds. They have to figure out one trait humans might have selected for in each breed, and why someone might have wanted that trait. Compare answers across groups. Drives home that artificial selection is driven by human goals (herding, hunting, guarding, companionship).

Materials: Printed dog breed photos, paper, pencils

Paper Clip Birds

Give each student a "beak" (tweezers, spoon, fork, straw). Scatter "seeds" of different sizes (rice, beans, paper clips, pasta). Students have 30 seconds to pick up as many seeds as possible with their beak. Compare which beak types worked best for which seeds. This mimics the finch adaptation Darwin saw: beak shape matches the available food.

Materials: Tweezers, spoons, forks, straws, rice, beans, paper clips, pasta, cups

Population Over Generations Sketch

Students draw a starting population of 10 "critters" with different traits (fur color, body size, leg length). They roll a die to decide what the environment selects for (for example, "predators hunt long-leg critters"). They remove selected individuals, then draw the next generation by redrawing the survivors twice each. Repeat for three generations. They see population traits shift on paper.

Materials: Paper, pencils, colored pencils, dice

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Texas Science Teacher Resource Hub

🚀 Jump to Your Grade

7th Grade TEKS Standards

Natural & Artificial Selection

💡 What This Standard Actually Means

⚠️ Misconceptions Your Students May Have

📓 Teaching Resources for 7.13D

🌎 Phenomenon Ideas for 7.13D

Every Breed of Dog Came From Wolves

Peppered Moths in Industrial England

Broccoli, Cauliflower, Cabbage, and Kale Are the Same Species

💡 Free Engagement Ideas for 7.13D

Bean Predator Simulation

Dog Breed Detective

Paper Clip Birds

Population Over Generations Sketch

Year-at-a-Glance Pacing Guides

Trusted Across Texas

Texas Schools and DistrictsLove Kesler Science

What Teachers Are Saying

Give Your Science Teachers Everything They Need

See It in Action

Texas Schools and Districts
Love Kesler Science