HS-ESS1-3NGSS*ScienceEarth and Space ScienceGrades 9-12
HS-ESS1-3: How Stars Make Elements Over Their Life Cycles
In plain English: HS-ESS1-3 is the NGSS high school performance expectation that asks students to communicate scientific ideas about how stars produce elements as they age. Students explain how the elements a star makes depend on its mass and life stage, from helium in every star to iron in massive stars and heavier elements in supernovae. It is usually taught in Earth and Space Science.
Communicate scientific ideas about the way stars, over their life cycle, produce elements.
Clarification Statement: Emphasis is on the way nucleosynthesis, and therefore the different elements created, varies as a function of the mass of a star and the stage of its lifetime.
Assessment Boundary: Details of the many different nucleosynthesis pathways for stars of differing masses are not assessed.
Next Generation Science Standards · Disciplinary Core Idea: Earth's Place in the Universe · Official standard
Students learn, and then explain to others, how stars make the elements. Every star fuses hydrogen into helium for most of its life, but what happens next depends on its mass. Stars like the sun go on to make carbon and oxygen and gently return part of their material to space. Stars above about 8 solar masses build heavier and heavier elements up to iron and then explode, spreading those elements and making some even heavier ones. Students practice communication throughout: infographics, short explanations for a younger audience, and corrections of flawed science writing.
The NGSS Clarification Statement says: "Emphasis is on the way nucleosynthesis, and therefore the different elements created, varies as a function of the mass of a star and the stage of its lifetime." The Assessment Boundary says: "Details of the many different nucleosynthesis pathways for stars of differing masses are not assessed." On this page students learn which elements come from which kind of star and which stage; the individual nuclear reactions are shown only as an illustration and are beyond this standard. Stellar masses are given in solar masses, and the 8-solar-mass dividing line is approximate. Values for stage lengths and abundances are rounded from stellar models and measurements, and data sets labeled invented are made up for teaching.
Learning Objectives
By the end of this lesson, students will be able to:
Explain that hydrogen and most helium formed in the Big Bang, while stars made nearly all heavier elements
Describe which elements a star makes at each life stage and how this depends on the star's mass
Explain how elements made in stars are returned to space and end up in new stars, planets and people
Use data on star composition and stage lengths as evidence in an explanation
Communicate these ideas accurately for a chosen audience, and correct inaccurate science writing
Prior Knowledge Required
Students should already be comfortable with:
Atoms, elements and the periodic table MS-PS1-1
The Big Bang as the source of hydrogen and helium HS-ESS1-2
Hand each student a periodic table and ask them to circle three elements in their own body: for example, calcium in bones, iron in blood and carbon in every cell.
Warm-Up Prompt
"The iron atoms in your blood are older than Earth. Where might they have been five billion years ago? Write your best guess and one question you would need answered to check it."
Collect a few guesses aloud. Common answers are "in the ground" or "from the Big Bang". Tell students that by the end of the lesson they will be able to trace the iron back to a specific kind of star.
Direct Instruction15-20 minutes
Where the elements start. The Big Bang made hydrogen, most of the helium and a trace of lithium. Everything else, from the carbon in DNA to the iron in blood, was made later by stars. Show Diagram 1 and walk through both paths.
Mass decides the path. Every star spends most of its life fusing hydrogen into helium in its core. When a star like the sun runs low on core hydrogen, its core contracts and heats up until helium fuses into carbon and oxygen; its outer layers later drift away, returning carbon, nitrogen and oxygen to space. A star above about 8 solar masses gets hot enough for carbon, neon, oxygen and silicon to fuse in turn, leaving layers like an onion around a core of iron. Fusing iron does not release energy, so the core collapses and the star explodes as a supernova. The explosion spreads elements from oxygen to iron and makes some heavier elements; collisions of neutron stars make others, such as much of the gold.
Counting parts to name a new element
Illustration only (the reaction steps are beyond this standard): in a red giant's core, three helium nuclei, each with 2 protons and a mass number of 4, end up as one nucleus. Which element is it?
Result: Protons: 3 × 2 = 6, so the element is carbon (atomic number 6), with mass number 3 × 4 = 12. Adding one more helium nucleus gives 8 protons: oxygen. This is why red giants are a source of carbon and oxygen.
Two stars, two sets of elements
Compare a star of 1 solar mass with a star of 20 solar masses. Which elements does each make in its core, and what does each leave behind?
Result: 1 solar mass: helium, then carbon and oxygen; it sheds its outer layers and leaves a carbon-oxygen white dwarf. 20 solar masses: helium, carbon, neon, oxygen, silicon and finally iron; it explodes as a supernova, leaving a neutron star or black hole, and spreads elements up to iron and beyond.
How long each stage lasts
Rounded stellar-model values for a 25-solar-mass star: hydrogen fusion 7,000,000 years, helium 700,000 years, carbon 500 years, neon 1 year, oxygen 0.5 year, silicon about 1 day. What fraction of the star's fusing life is spent on hydrogen?
Result: 7,000,000 ÷ (7,000,000 + 700,000 + 500 + 1 + 0.5 + 0.003) ≈ 0.91, so about 91%. Each later stage is much shorter, and the iron core builds up in about a day.
Reading the sun's composition
Measurements of the sun's spectrum, rounded: hydrogen 73.8% and helium 24.9% of its mass, with oxygen, carbon, neon, iron and other heavier elements making up the rest. What share is heavier elements, and where did they come from?
Result: 100% - 73.8% - 24.9% = 1.3%. The sun's core has only fused hydrogen so far, and its outer layers have not mixed with the core, so these heavier elements were already in the cloud the sun formed from: they were made by earlier generations of stars.
Fixing a sentence for a general audience
A student's poster says: "Stars make every element in the universe, including hydrogen." Rewrite it so it is accurate and still easy to read.
Result: Revision: "Hydrogen and most helium formed in the Big Bang. Stars made almost all the heavier elements, like the carbon in your cells and the iron in your blood." The revision keeps the short style but fixes the claim.
After the examples, ask students to add one sentence to their warm-up guess about the iron in their blood. Listen for the idea that iron is built in the cores of massive stars and spread by supernovae.
Guided Practice15 minutes
Pairs sort six star cards by mass and, for each, predict the heaviest element its core will make, what it leaves behind, and which elements it returns to space. Use the approximate dividing lines: stars below about 0.5 solar masses never get hot enough to fuse helium, stars from about 0.5 to 8 solar masses make carbon and oxygen and end as white dwarfs, and stars above about 8 solar masses build iron cores and explode.
Guided practice star cards
Card
Mass (solar masses)
Heaviest core element
Remnant
A
0.3
Students decide
Students decide
B
1
Students decide
Students decide
C
3
Students decide
Students decide
D
6
Students decide
Students decide
E
10
Students decide
Students decide
F
25
Students decide
Students decide
Place the cards in order of mass and draw the two dividing lines at about 0.5 and 8 solar masses.
Fill in the heaviest core element and the remnant for each card.
Circle the cards whose stars return iron to space, and underline the cards that return carbon and nitrogen in gently expelled outer layers.
Write one sentence a museum visitor could read that explains why card F makes more kinds of elements than card B.
Expected sort: A makes only helium (and has not finished its main sequence in the age of the universe); B, C and D make carbon and oxygen and end as white dwarfs; E and F build iron cores and explode as supernovae. Ask pairs to justify each boundary card with the mass rule.
Independent Practice10-15 minutes
Each student uses Diagram 2 and the approximate make-up of the human body by mass: oxygen 65%, carbon 18%, hydrogen 10%, nitrogen 3%, calcium 1.5%, phosphorus 1% and other elements 1.5%.
Students (1) compute the percent of their body mass that is elements made in stars (everything except hydrogen), (2) name the kind of star that made the oxygen and the calcium, and (3) write a 100-150 word explanation for a seventh grader titled "Where your atoms were made". The explanation must use one number from Diagram 2 and one number from the body table as evidence.
Closure5 minutes
Exit ticket, 3-2-1: three elements and the kind of star that made each, two ways elements get from a star back into space, and one question you still have. Share a few questions and sort them into ones the class can answer now and ones for further research.
Differentiation Strategies
For Struggling Students
Give a partly filled copy of Diagram 1 with blanks for the elements at each stage
Provide sentence starters for the explanation: "The ___ in my body was made in a ___ star during its ___ stage."
Use a periodic table colored by origin so students can check each element before writing
For Advanced Students
Ask students to research how a neutron-star collision observed in 2017 provided evidence for where heavy elements such as gold form, and summarize it in three sentences
Have students explain, using the stage lengths, why the silicon stage of a massive star is so short
Ask students to write the same explanation twice, for a seventh grader and for a science museum placard, and compare their word choices
Assessment Guidance
What to Look For
Check that students tie each element to a kind of star and a stage, not just to "stars" in general, and that mass is the deciding factor in their explanations. Look for clear communication: accurate claims, a sensible order, and evidence such as composition data or stage lengths. Listen for students who say the Big Bang made all elements, who think stars start with iron, or who expect the sun to become a supernova.
02
Classroom Activities
3 Activities
1
Infographic: Two Stars, Two Recipes
30 minGroups of 3
Groups design a one-page infographic that compares the life of a star like the sun with the life of a star of about 20 solar masses. The goal is a design that a visitor can understand in one minute without losing accuracy.
Requirements
Show each life stage in order, with the elements made in the core at that stage.
Show how each star returns elements to space and what it leaves behind.
Include one number as evidence, such as a stage length or a composition value, with its source in the lesson.
Use no more than 120 words in total.
Peer Review
Each group swaps with another and checks: Is every claim accurate? Is the difference caused by mass clearly stated? Could a middle school student follow the order?
Reviewers write one strength and one specific fix. Groups revise before posting.
Modification for Distance Learning
Groups build the infographic in a shared slide, record a 60-second voice-over, and post both. Classmates leave one question in the comments that the group answers.
2
Timeline Strip: The Last Days of a Massive Star
20 minGroups of 3-4
Groups lay out the stages of a 25-solar-mass star on a strip of register tape at a scale of 1 m for every million years, using the rounded stage lengths from the lesson. The strip turns the abstract numbers into something students can walk along.
Procedure
Hydrogen stage, 7,000,000 years: measure 7 m of tape and label it.
Helium stage, 700,000 years: add 0.7 m.
Carbon stage, 500 years: add 0.5 mm. Neon (1 year), oxygen (0.5 year) and silicon (about 1 day) are far too short to measure; mark them with a single pencil line and a label.
Label each segment with the element made and the element left as ash.
Discussion Questions
The hydrogen and helium segments together are 7.7 m, while the carbon, neon, oxygen and silicon stages together are shorter than 1 mm. What does that tell you about when a massive star makes most of its heavy elements?
If astronomers look at many massive stars at random, why do they almost never catch one in the silicon stage?
How would you change the strip so that a museum visitor could see the last stages?
Challenge Variation
Groups make a second strip for the same stages on a scale in which the carbon stage is 1 m long, and explain what is gained and lost with each scale.
3
Science News Editors
25 minPairs
Pairs act as editors for a science news site. Each pair receives three short invented news blurbs about stars and elements, finds the errors, and rewrites each blurb so it is accurate and still engaging.
Blurb Cards (invented)
Blurb 1: "Astronomers say our sun will one day explode, scattering gold across the galaxy."
Blurb 2: "All the oxygen you breathe was made in the first minutes after the Big Bang."
Blurb 3: "Iron is the easiest element for stars to make, so young stars start by making iron."
Editing Steps
Underline each false or misleading claim and write the correct idea beside it, citing the lesson (Diagram 1, the examples or the stage lengths).
Rewrite each blurb in 30 words or fewer.
Trade with another pair and check each other's rewrites for accuracy.
Discussion Questions
Which error in the blurbs would be hardest for a general reader to notice, and why?
How can a writer keep a sentence exciting without making it false?
Modification for Distance Learning
Post the blurbs in a shared document with suggestion mode turned on, so pairs edit in place and classmates can see each change.
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: How a Star's Mass Decides Which Elements It Makes
Two life paths starting from the same kind of gas cloud. Stars of about 0.5 to 8 solar masses make carbon and oxygen and return carbon, nitrogen and oxygen gently; stars above about 8 solar masses build up to iron and return their elements in a supernova. The returned elements end up in the next generation of stars and planets.
Diagram 2: Heavier Elements in the Sun
The seven most abundant elements heavier than helium in the sun, as percent of its mass, drawn to scale from rounded measurements of its spectrum. Together with the elements not shown, they make up about 1.3% of the sun. They were made by earlier generations of stars.
04
Homework Assignment
~30 min
HS-ESS1-3 Homework: Explaining Where Elements Come From
Directions: Use the approximate dividing lines from the lesson (0.5 and 8 solar masses). Stage lengths and abundances are rounded model values or invented data, as labeled. Write for the audience named in each problem, and back each claim with a number or a stage from the lesson.
Part 1: Mass and Elements (Problems 1-2)
Star cards: 0.4, 1.5, 4, 9, 15 and 40 solar masses. (a) Sort them into three groups: never fuse helium, end as white dwarfs, end as supernovae. (b) For each group, name the heaviest element made in the core. (c) Which groups return iron to space? Explain in two sentences.
Write a short paragraph (60-100 words) for a museum placard next to a diamond, explaining where the carbon in it was made. Name the kind of star, the stage and how the carbon left the star.
Part 2: Life Stages (Problems 3-4)
Rounded model values for a 15-solar-mass star: hydrogen fusion 11,000,000 years, helium 1,500,000 years, carbon 3,000 years, neon 1 year, oxygen 2 years, silicon about 10 days. (a) What percent of its fusing life is the hydrogen stage? (b) How many times longer is the helium stage than the carbon stage? (c) Explain what these numbers mean for where and when the star makes its heavier elements.
A classmate draws a massive star just before it explodes with one core of mixed elements. Describe how to fix the model: name the layers from the outside in, the element made in each, and why iron is at the center.
Part 3: Evidence and Recycling (Problems 5-6)
Invented data on five stars give the share of their mass that is elements heavier than helium: a 12-billion-year-old star 0.01%, a 10-billion-year-old star 0.1%, an 8-billion-year-old star 0.4%, the sun (4.6 billion years) 1.3%, and a 1-billion-year-old star 1.6%. (a) Describe the trend. (b) How many times more heavy elements does the sun have than the oldest star? (c) Explain the trend using the recycling of elements between generations of stars.
The invented spectrum of a supernova remnant shows ejected oxygen 1.8, silicon 0.15, sulfur 0.08 and iron 0.10 solar masses. (a) Which element was ejected in the largest amount? (b) One solar mass is about 333,000 Earth masses. How many Earth masses of oxygen is that? (c) Write two sentences for a news article that use these numbers to explain what the exploding star gave back to space.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
Accuracy
Every element is tied to the right kind of star and stage, with mass as the deciding factor
Mostly accurate, with one misplaced element or stage
Use of Evidence
Uses numbers from the data (stage lengths, abundances, ejected masses) correctly to support claims
Numbers computed but not used to support a claim, or one calculation error
Communication
Clear, well-ordered writing suited to the named audience and within the word limit
Understandable but disorganized, or not suited to the audience
05
Quiz: 20 Questions
Interactive, with answers
Instructions
Use the approximate dividing lines of 0.5 and 8 solar masses from the lesson. Stage lengths and data are rounded or invented, as labeled. Your score updates as you answer, and Reset quiz clears everything so you or your students can try again.
Multiple choice: pick an option to check it. Short answer: write your answer, then reveal the model answer.
0 of 20 answered · 0 correct
Question 1 of 20 · Multiple Choice
The oldest stars known contain almost nothing but hydrogen and helium, with only tiny traces of heavier elements. What does this evidence suggest?
Answer: C
Stars keep the composition of the gas they formed from, so the earliest gas was almost pure hydrogen and helium, the elements the Big Bang made. Choice A is contradicted by the tiny traces of carbon and oxygen in those stars. Choice D reverses the trend: younger stars have more heavy elements, not fewer.
Question 2 of 20 · Multiple Choice
During the main sequence, what do the cores of all stars do?
Answer: A
Every star spends its main sequence fusing hydrogen into helium; only the rate depends on mass. Choice B happens later, in red giants and supergiants. Choice D describes fission, which is not how stars shine.
Question 3 of 20 · Multiple Choice
A star of 2 solar masses has used up the hydrogen in its core. What do models predict its core does next?
Answer: B
At 2 solar masses the star is between about 0.5 and 8 solar masses, so after the main sequence its core becomes hot enough for helium fusion, which makes carbon and oxygen. Choice A describes stars above about 8 solar masses. Choice D is impossible: fusion does not run backward in a star.
Question 4 of 20 · Multiple Choice
A star has 12 solar masses. Which prediction fits the lesson's model?
Answer: D
At 12 solar masses the star is above the 8-solar-mass line, so its core gets hot enough to build elements up to iron before collapsing. Choice A applies to stars between about 0.5 and 8 solar masses. Choice B applies only below about 0.5 solar masses.
Question 5 of 20 · Multiple Choice
Why does the chain of fusion stages in a massive star's core end at iron?
Answer: B
Fusing elements up to iron releases energy, but fusing iron does not, so once the core is iron nothing supports it against gravity and it collapses. Choice A is wrong: iron piles up in the core. Choice D is wrong because hydrogen ran out in the core millions of years earlier.
Question 6 of 20 · Multiple Choice
Where are elements heavier than iron, such as gold, mainly made?
Answer: C
These elements need conditions found only in exploding massive stars and in neutron-star collisions. Choice A is wrong because main-sequence cores make only helium. Choice D confuses where iron collects in planets with where elements are made.
Question 7 of 20 · Multiple Choice
Rounded model values for a 20-solar-mass star: hydrogen stage 8,000,000 years, helium 900,000 years, carbon 1,000 years, oxygen about 1 year. About what percent of these years is the hydrogen stage?
Answer: B
8,000,000 ÷ 8,901,001 ≈ 0.899, about 90%. Choice A assumes the stages are about equal. Choice D forgets the 900,000-year helium stage.
Question 8 of 20 · Multiple Choice
Invented data: stars in Cluster X have 0.02% of their mass in heavy elements, and stars in Cluster Y have 1.0%. What is the best inference?
Answer: A
Each generation of stars adds heavy elements to the gas, so gas that formed stars earlier had fewer of them. Choice B reverses the trend: stars keep the composition of the gas they formed from on their surfaces. Choice D confuses composition with distance.
Question 9 of 20 · Multiple Choice
Use Diagram 2. About how many times the mass of carbon does the sun contain in oxygen?
Answer: C
0.57% ÷ 0.24% ≈ 2.4. Choice A divides carbon by oxygen instead. Choice B misplaces the decimal point.
Question 10 of 20 · Multiple Choice
Which sentence would be the most accurate for a middle school science magazine?
Answer: D
Hydrogen dates from the Big Bang, and the heavier atoms in the body were made by earlier stars and were already in the cloud that formed the solar system. Choice B is wrong because the sun has not yet returned any elements to space. Choice A names the Big Bang, which made only the lightest elements.
Question 11 of 20 · Multiple Choice
Spectra of a glowing shell of gas around a small, hot white dwarf show more carbon and nitrogen than the sun's surface has. What is the best explanation?
Answer: A
A white dwarf is the leftover core of a star of about 0.5-8 solar masses, and the shell is the outer layers it gave off, enriched with elements the star made. Choice B does not fit, because supernovae leave neutron stars or black holes, not white dwarfs. Choice D is wrong: Big Bang gas contains almost no carbon or nitrogen.
Question 12 of 20 · Multiple Choice
Which observation is evidence that supernovae spread newly made elements into space?
Answer: D
Spectral lines identify the elements, and their shifts show the gas moving outward fast. Choice A shows the explosion is energetic but says nothing about elements. Choices B and C are true but unrelated.
Question 13 of 20 · Multiple Choice
A red dwarf star has 0.15 solar masses. Which elements has its core made so far?
Answer: C
Below about 0.5 solar masses a star never gets hot enough to fuse helium, and red dwarfs burn so slowly that none has finished its main sequence. Choice B applies to stars of about 0.5-8 solar masses. Choices A and D need massive stars or neutron-star collisions.
Question 14 of 20 · Multiple Choice
A massive star spends millions of years fusing hydrogen but only about a day fusing silicon. Which explanation fits?
Answer: B
Later fuels give less energy per kilogram, the core has less of each, and the star is losing energy very fast, so the stages get shorter and shorter. Choice A reverses the energy comparison. Choice D is wrong: each stage happens in the core.
Question 15 of 20 · Short Answer
In three or four sentences, explain to a younger brother or sister where the oxygen they breathe was made. Use accurate science and simple words.
Model answer: "The oxygen you breathe was made inside stars, long before Earth existed. Stars squeeze light elements together to make heavier ones. Some stars make oxygen as they grow old, and the biggest stars make a lot of it and blast it into space when they explode. That oxygen mixed into the cloud of gas that became our sun and Earth." Rubric: full credit names stars (not the Big Bang), explains that oxygen was released into space, and links it to the cloud that formed the solar system, in clear language.
Question 16 of 20 · Short Answer
A 60 kg student's body is about 65% oxygen and 18% carbon by mass. How many kilograms of each is that? Name the kinds of stars that made them.
Oxygen: 0.65 × 60 = 39 kg. Carbon: 0.18 × 60 = 10.8 kg. Both were made in stars: carbon and oxygen in the cores of red giants (stars of about 0.5-8 solar masses) and in massive stars, whose supernovae also release large amounts of oxygen.
Question 17 of 20 · Short Answer
Three stars have masses of 0.8, 5 and 30 solar masses. For each, name the heaviest element its core will make and what it leaves behind.
0.8 solar masses: carbon and oxygen, leaving a white dwarf (after a very long main sequence). 5 solar masses: carbon and oxygen, leaving a carbon-oxygen white dwarf. 30 solar masses: iron, then a supernova that leaves a neutron star or black hole. The 8-solar-mass line separates the last star from the other two.
Question 18 of 20 · Short Answer
A classmate's infographic says: "When the sun dies, it will make the iron for future planets." Evaluate the claim using the mass rule, and rewrite the sentence so it is accurate.
The claim is inaccurate: the sun, at 1 solar mass, is below the 8-solar-mass line, so its core will only get as far as carbon and oxygen, and it will shed its outer layers gently instead of exploding. Iron is built in the cores of stars above about 8 solar masses and spread by supernovae. Rewrite: "When the sun dies, it will return carbon, nitrogen and oxygen to space; the iron in future planets will come from massive stars that explode."
Question 19 of 20 · Short Answer
A textbook caption says: "Massive stars fuse hydrogen directly into iron." Rewrite the caption so it is accurate, in one or two sentences.
Model revision: "Massive stars fuse hydrogen into helium, then in later stages fuse helium, carbon, neon, oxygen and silicon in turn, building up heavier elements until the core is iron." Full credit keeps the stages in order and ends at iron.
Question 20 of 20 · Short Answer
Write a paragraph (5-6 sentences) comparing the life of a 2-solar-mass star with that of a 15-solar-mass star, focusing on the elements each one makes and how those elements reach space.
Model answer: Both stars spend most of their lives fusing hydrogen into helium, but the massive star does it much faster. The 2-solar-mass star later becomes a red giant and fuses helium into carbon and oxygen. It returns carbon, nitrogen and oxygen gently when its outer layers drift away, and a white dwarf remains. The 15-solar-mass star fuses carbon, neon, oxygen and silicon in turn until its core is iron. Then the core collapses, and the supernova spreads elements up to iron and makes some heavier ones. Mass is what decides how far each star's element-building goes. Rubric: full credit gives the stages in order for both stars, the elements at each stage, how each returns elements, and mass as the cause.
0 of 20 answered · 0 correct
06
Frequently Asked Questions
10 Questions
What does HS-ESS1-3 mean?
HS-ESS1-3 asks students to communicate scientific ideas about how stars produce elements over their life cycle. The code means High School, Earth and Space Science, core idea 1 (Earth's Place in the Universe), performance expectation 3. Students explain, in writing, speech or graphics, how the elements made depend on a star's mass and stage.
Is HS-ESS1-3 taught in Earth science or chemistry?
It is usually taught in Earth and Space Science, in an astronomy unit after the sun and the Big Bang. It also fits well in Chemistry when the class studies the periodic table, because it explains where the elements came from.
Do students need to know nuclear reaction pathways for HS-ESS1-3?
No. The Assessment Boundary says the details of the many nucleosynthesis pathways are not assessed. Students should know which kinds of stars make which elements and at which stage, not the step-by-step reactions or their names.
What does "communicate scientific ideas" look like in HS-ESS1-3?
It means students produce something another person can learn from: an infographic, a short explanation for a younger audience, a museum placard, a podcast script or a corrected news article. Good work is accurate, well ordered, suited to its audience and backed by evidence.
How is HS-ESS1-3 different from HS-PS1-8?
HS-PS1-8 is a physical science standard about modeling changes in the nucleus during fission, fusion and radioactive decay. HS-ESS1-3 uses the idea of fusion to explain where the elements came from across a star's life. The two support each other, but HS-ESS1-3 does not require nuclear equations.
What is the difference between a nova and a supernova?
A nova is a surface outburst on a white dwarf that pulls gas from a companion star; the white dwarf survives and can erupt again. A supernova destroys most or all of a star. Novas are mentioned here only to avoid confusion, since the word sounds similar.
Why is the 8-solar-mass dividing line only approximate?
Because a star's fate also depends on things like how much mass it loses during its life, whether it has a close companion and its starting composition. Models place the line near 8 solar masses, and students can treat it as a useful rule of thumb.
How much class time does HS-ESS1-3 need?
One lesson like this one introduces the ideas, and a second period is useful for the communication product and peer review. Many teachers combine HS-ESS1-3 with HS-ESS1-1 and HS-ESS1-2 in a single unit on stars and the universe.
What should a student infographic for HS-ESS1-3 include?
The stages of at least two stars of different mass in order, the elements made at each stage, how the elements get back into space, and at least one piece of evidence with a number. It should be readable in about a minute and contain no false shortcuts.
How does HS-ESS1-3 connect to later science courses?
In Chemistry it explains why some elements are common and others rare. In Earth science it leads to how Earth formed from material made by earlier stars (HS-ESS1-6). In Physics it connects to nuclear energy and the conservation of mass and energy.
07
Related Standards
5 standards
These standards connect to HS-ESS1-3: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
MS-PS1-1Prerequisite
Develop models to describe the atomic composition of simple molecules and extended structures
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