The Natural Selection

Welcome to The Natural Selection — your top choice for keeping science education evolving and thriving across our district! In each issue, you’ll find essential curriculum updates, upcoming training opportunities, and practical classroom resources designed to help you adapt and excel. This newsletter is built entirely to support and empower you, our high school science teachers, as you guide students through an engaging and dynamic year of discovery!

Click the button below to access the survey. It will take approximately 3-5 minutes to complete.

Misconceptions:

• Students focus on the length of the DNA sequence (e.g. Mutation 1 changes 3 bases vs. Mutation 2 changes 2 bases) rather than analyzing how the reading frame shifts downstream of the mutation.
• Students could identify the correct mutation, but lacked the precise genetic vocabulary or conceptual understanding to explain how a frameshift alters the downstream amino acid sequence.

Test Strategy:

• Adapt CER specifically for Biology SCRs using "Claim, Evidence, Effect" (CEE):
• State the core answer (Claim)
• Cite the specific codon or base sequence change (Evidence)
• Explain the functional outcome on the protein or trait (Effect)

Quick Classroom Activity (3-5 minutes):

• Hand students mini-whiteboards to transcribe Mutation 1 and Mutation 2 into mRNA and look up the amino acids on a codon chart to identify the altered proteinThen, have them look up the resulting amino acids on a codon chart to visually show which one alters the protein sequence.
• Then, have them write a one-sentence Effect statement using at least two bolded target terms (frameshift, codon sequence, or amino acids) from a projected Word Bank before holding up their boards.

We want all of our students to earn the full 2 points on short constructed response (SCR) items both on district assessments and on the Biology EOC exam. Below is a ~3 minute video and a one-pager with SCR strategies you can use that will require only minor adjustments in your instructional routine. Click the images below to view each resource!

Did you notice the addition of the red text in the Content Specificity column on the Biology TEKS Specificity Chart?

The red text indicates content that is included in a Boundary statement in the TEA TEKS Guide. In order for students to earn either Meets or Masters on the Biology EOC, students must be exposed to the information in the red text, as items beyond TEA's identified boundaries can appear on the Biology EOC exam.

Please ensure your students receive instruction over ALL content on the TEKS Specificity Chart.

• On the first page of the IPC, you will find ELPS and Language Objectives listed for each lesson.
• Biology, Chemistry, & Physics teachers - Below the daily lesson links, you will find links to short, student-centered activities for select lessons. Biology teachers will also find short activities that spiral other standards into select lessons.

The Next-Level Nudge is your monthly reminder to ensure fundamental science concepts are not just taught, but deeply understood and retained. Each month, we’ll spotlight a critical topic in Biology, Chemistry, Physics, and Environmental Systems that often serves as a keystone for future units or a common hurdle on district and state assessments. For each subject, we provide five core components:

• What - the specific, essential concept
• Watch Out For - a common student misconception
• How to Teach It - a practical, concept-specific teacher action
• Student Engagement - a low-prep, concept-specific student activity
• Hands-On Activities - investigations from your online resources or another low-prep activity

Our goal is to give you a quick, actionable check to ensure your students have the foundational knowledge and advanced critical thinking skills necessary for success.

• WHAT - Gene Expression & Protein Synthesis: Describe the significance of gene expression and explain the process of protein synthesis using models of DNA and ribonucleic acid (RNA). Students must trace how genetic information flows from DNA to mRNA during transcription, and from mRNA to amino acid sequences (proteins) during translation.

• WATCH OUT FOR - Students often confuse the distinct roles and locations of transcription (nucleus) versus translation (ribosome), or assume that amino acids are synthesized directly from nucleic acids rather than assembled using tRNA codons. Additionally, students frequently view gene expression as a static, continuous process rather than a highly regulated cellular response to internal and external environmental signals.

• HOW TO TEACH - Use physical or digital sequence models (like paper codon strips or digital base-pairing manipulatives). Have students transcribe DNA base sequences into complementary mRNA codons, then use a codon wheel/chart to translate those codons into specific amino acid chains.

• STUDENT ENGAGEMENT - "Codon Decoder" Prompt: Present an mRNA sequence on the board. Have students use whiteboards to transcribe the DNA template into mRNA, identify the corresponding tRNA anticodons, use a genetic code chart to determine the resulting amino acid sequence, and explain why protein structure relies on accurate translation.

• HANDS-ON ACTIVITIES -

- Transcription & Translation Modeling (Cut-Outs)

- Virtual Lab: DNA and RNA Structure

• WHAT - VSEPR Theory & Molecular Geometry: Classify and draw electron dot structures for molecules with linear, bent, trigonal planar, trigonal pyramidal, and tetrahedral molecular geometries as explained by Valence Shell Electron Pair Repulsion (VSEPR) theory. Students must determine total valence electrons, draw valid Lewis dot structures, identify bonding/lone pairs on central atoms, and assign the correct 3D geometry.

• WATCH OUT FOR - Students often neglect unshared (lone) electron pairs on the central atom when determining 3D geometry, treating bent molecules as linear or trigonal pyramidal as trigonal planar. They also frequently confuse a molecule's electron pair geometry with its actual molecular shape.

• HOW TO TEACH - Combine 2D Lewis structure drawings directly with 3D molecular modeling kits or balloon models. Explicitly show how lone pairs exert stronger electrostatic repulsion than bonding pairs, forcing bonded atoms closer together into specific molecular shapes.

• STUDENT ENGAGEMENT - "Predict the Geometry" Prompt: Display chemical formulas (CH4, NH3, H2O, CO2, BF3) on the board. Have students draw the Lewis dot structure on mini-whiteboards, count the bonding regions and lone pairs around the central atom, and state the resulting VSEPR molecular geometry.

• HANDS-ON ACTIVITIES -

- ChemLab: Modeling Molecular Shapes

- PhET Simulation: Molecular Shapes

• WHAT - One-Dimensional Motion & Kinematics: Describe and analyze motion in one dimension using equations with the concepts of distance, displacement, speed, velocity, frames of reference, and acceleration, with a specific focus on frames of reference and kinematic applications. Students must establish coordinate systems and apply kinematic equations to quantify motion relative to different observational frames.

• WATCH OUT FOR - Students often struggle to recognize that motion is relative to the chosen frame of reference, assuming velocity is absolute. They also frequently mix up positive/negative signs for direction, vector acceleration, and reference frame movement when solving one-dimensional kinematics problems.

• HOW TO TEACH - Use real-world reference frame scenarios (e.g., walking forward inside a moving bus vs. watching from the sidewalk). Teach students to explicitly define an origin, positive direction, and observer's frame of reference prior to selecting kinematic equations or vector signs.

• STUDENT ENGAGEMENT - "Frame Switch" Prompt: Show a video clip or diagram of a passenger walking forward on a moving train. Have students write on mini-whiteboards the passenger's velocity relative to (1) a seated passenger and (2) an observer standing on the platform, justifying their frame-of-reference choice using vector addition.

• HANDS-ON ACTIVITIES

• WHAT - Resource Use & Conservation: Document the use and conservation of both renewable and non-renewable resources as they pertain to sustainability. Students must evaluate resource consumption patterns, quantify depletion rates, and analyze management practices that promote long-term ecological balance and sustainability.

• WATCH OUT FOR - Students often oversimplify "renewable" resources as infinite and indestructible, failing to understand that resources like timber or groundwater can be depleted if extraction exceeds the natural replenishment rate. They also struggle to distinguish between simple conservation and broader ecological sustainability.

• HOW TO TEACH - Frame resource consumption through life-cycle analysis and sustainability matrices. Have students categorize energy and material resources, calculate sustainability rates (consumption rate vs. regeneration rate), and evaluate real-world trade-offs in resource management.

• STUDENT ENGAGEMENT - "Resource Audit" Prompt: Provide data showing extraction rates and natural regeneration rates for two resources (e.g., an aquifer vs. a solar array). Have students use mini-whiteboards to draft a 3-sentence analysis evaluating whether current usage is sustainable and recommending one concrete conservation policy.

• HANDS-ON ACTIVITIES -

• "Tragedy of the Commons" Resource Depletion Challenge (10–15 mins):

  • Setup: Place pairs or small groups of students around a central bowl containing 20 small tokens or beads (representing a renewable resource, like fish or groundwater). Provide each student with a mini-whiteboard to track their yield.

  • The Task:

    • Round 1 (Unregulated Harvest - 3 mins): Conduct two 15-second harvesting intervals where students can quietly remove 1 to 4 tokens per turn. Between rounds, double any remaining tokens in the bowl (up to a max capacity of 20). Have students record their group's totals and note if the resource collapsed.

    • Round 2 (Sustainable Management Strategy - 5 mins): Reset the bowl to 20 tokens. Give groups 2 minutes to discuss and establish an extraction rule or quota before repeating the harvest steps to maintain the resource indefinitely.

  • Debrief (3–5 mins): Students write a 1-sentence takeaway on their mini-whiteboards explaining how management rules convert an overexploited resource into a sustainable one.

You are invited to the annual Dallas Arboretum Educator Open House!

Enjoy a Family Day on September 26, 2026 from 9 am to 1 pm.

For more information and to register, see this flyer.

The Dallas ISD Environmental Education Center (EEC) is hosting its annual open house on Saturday, October 17, 2026 from 10 am - 2 pm. Bring your family and enjoy a fish fry, tour the grounds, meet the animals, and learn about all that the EEC has to offer!

For more information and to RSVP, see this flyer.

Here are important assessment dates to add to your calendar for the first semester:

• Biology: Standards Master Check Testing Window - September 28 - October 2
• Biology EOC Retesters: STAAR EOC Testing Window - November 30 - December 4
• Biology, Chemistry, Physics, Environmental Systems: Assessment of Course Performance Testing Window - December 14 - December 18

For more information, visit the Dallas ISD Assessment website.

Do you teach Biology, Chemistry, Physics, or IPC?

Do you use Google Classroom?

You can easily assign student engagement activities from McGraw Hill directly into Google Classroom using a few easy steps. Just follow the steps in the video below!

Ready to Help Your Lessons Evolve?

My door is always open for office hours! Think of me as your partner in the field. I'm here to help you explore our online curriculum resources, cultivate engaging new student activities, or offer targeted content support whenever you need a boost.

Please contact me directly at cycurtis@dallasisd.org to set up a time to collaborate. Whether in-person or virtual, I’m here to support your growth and help your teaching flourish this year!