HS-LS3-1: How DNA and Chromosomes Carry Traits
Also called NGSS HS-LS3-1 · Topic: Inheritance and Variation of Traits · Life Science
The Official Wording
Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.
Assessment boundary: Assessment does not include the phases of meiosis or the biochemical mechanism of specific steps in the process.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What HS-LS3-1 Means in Plain English
Students ask sharp, testable questions about how traits pass from parents to children. Along the way they sort out the relationships: chromosomes are long DNA molecules, genes are stretches of that DNA, and most genes hold instructions for a protein that shapes a trait.
The phases of meiosis and the chemistry of each step are left out, since the goal is the big picture of inheritance. It builds on MS-LS3-1 and MS-LS3-2 and leads to HS-LS3-2, where students explain where new variation comes from.
HS-LS3-1 I Can Statements
- I can explain how DNA, genes and chromosomes are related.
- I can ask questions about how traits pass to offspring.
- I can explain why each parent gives half of a child's chromosomes.
HS-LS3-1 Worked Example
A DNA extraction from strawberries that gives students something real to see before they start asking questions.
What does DNA look like, and what questions does seeing it raise about inheritance?
Set It Up: Ripe strawberries, zip bags, a mix of water, dish soap and salt, cheesecloth, test tubes and ice-cold ethanol.
- Mash one strawberry in a zip bag with the soap and salt mix for two minutes.Soap breaks open cell membranes
- Strain the mash through cheesecloth into a test tube.Clear pink liquid
- Slowly pour cold ethanol down the side of the tube to form a top layer.White, stringy threads rise into the ethanol
- Lift the threads on a wooden stick and write questions about what they are and how they reach the seeds.“Why does every cell need a copy?”
- Sort the questions into ones the class can test, research or model.Question board in three columns
Strawberry cells hold so much DNA that it clumps into threads visible without a microscope, and seeing it led to questions about genes, chromosomes and seeds.
Why it works: DNA is a long molecule packed into chromosomes in every cell, and the instructions it carries are copied into the seeds that grow the next plants.
Common Mistakes with HS-LS3-1
Mixing up DNA, genes and chromosomes
“A gene is a kind of chromosome”
Try this: Picture a chromosome as one long DNA molecule and a gene as one section of it, like a chapter in a book.
Questions that cannot be investigated
“Why is DNA so cool?”
Try this: Rewrite questions so evidence can answer them, like asking how many chromosomes a sperm or egg cell carries compared with a body cell.
One gene, one trait, always
“There is a single gene for height”
Try this: Many traits, like height and skin color, depend on many genes plus the environment, while a few traits follow one gene.
Where HS-LS3-1 Fits
Practice HS-LS3-1
Quick Check
- How many chromosomes does a human body cell have, and how many come from each parent?
- What is a gene?
- Why do children look like both parents but not exactly like either?