MS-ESS1-1NGSS*ScienceEarth and Space ScienceGrades 6-8
MS-ESS1-1: Modeling Moon Phases, Eclipses and Seasons
In plain English: MS-ESS1-1 is the NGSS middle school performance expectation that asks students to develop and use a model of the Earth-sun-moon system to describe the repeating patterns of moon phases, solar and lunar eclipses, and seasons. Students build lamp-and-ball, flashlight and calendar models and use them to explain and predict. It is usually taught in middle school Earth and space science.
Develop and use a model of the Earth-sun-moon system to describe the cyclic patterns of lunar phases, eclipses of the sun and moon, and seasons.
Clarification Statement: Examples of models can be physical, graphical, or conceptual.
Next Generation Science Standards · Disciplinary Core Idea: Earth's Place in the Universe · Official standard
Students build and use models of the Earth-sun-moon system to explain three patterns that repeat: the phases of the Moon (the changing shape of its lit part as seen from Earth), eclipses (when one body moves into the shadow of another) and the seasons. A model is a simplified version of a real system that we can use to explain and predict. Students make a physical model with a lamp and foam balls, a graphical model from a moon journal and an eclipse calendar, and a conceptual model in labeled drawings, and they use each one to make a prediction they can check.
The NGSS Clarification Statement says: "Examples of models can be physical, graphical, or conceptual." This performance expectation has no Assessment Boundary. The page stays with patterns students can see and explain with the model: no orbit equations. Astronomy values (the 29.5-day cycle of phases, the 23.4° tilt of Earth's axis, Earth's distance from the Sun) are published values, rounded, and eclipse dates are real dates in Universal Time. Data sets marked invented are made up for teaching. Safety rule for the whole unit: students never look at the Sun, not even through filters, sunglasses or eclipse glasses. They observe solar eclipses only with a pinhole projector, standing with their back to the Sun, or on a live video stream.
Learning Objectives
By the end of this lesson, students will be able to:
Use a lamp-and-ball model to explain why the Moon shows phases in a cycle of about 29.5 days, and predict the date of a later phase
Use a model to explain why solar eclipses happen only at new moon, lunar eclipses only at full moon, and why eclipses do not happen every month
Use the tilt of Earth's axis to explain the yearly cycle of seasons, including why the hemispheres have opposite seasons
Analyze data from a model (shadow area, noon Sun height, eclipse dates) and critique a model that cannot explain an observation
Prior Knowledge Required
Students should already be comfortable with:
Daily patterns of shadows, day and night, and the changing night sky over the year 5-ESS1-2
Earth spins on its axis once a day and travels around the Sun once a year
The Moon travels around Earth and shines only by reflecting sunlight
Reading a calendar, a table and a line graph, and measuring angles with a protractor
Show a photo of a half-lit Moon (a quarter moon) next to a photo of a full moon. Ask students to write an answer on their own before talking.
Warm-Up Prompt
"A classmate says the Moon looks like a half circle tonight because Earth's shadow is covering the other half. What would you expect to see if that idea were right? How could we test it?"
Collect a few ideas. Many students hold this "shadow idea." Don't correct it yet. Write it on the board as a claim to test. Point out one clue: the Moon is often half lit in the afternoon sky, when Earth's shadow points away from both the Sun and the Moon. Tell students that by the end of class they will test the shadow idea with a model.
Direct Instruction15 minutes
Key words. An orbit is the path one object takes around another. The Moon orbits Earth, and Earth orbits the Sun. Rotation is spinning on an axis (an imaginary line through the North and South Poles). Half of the Moon is always lit by the Sun. A phase is how much of that lit half we can see from Earth. Waxing means the lit part we see is growing; waning means it is shrinking. A crescent is less than half lit, and a gibbous moon is more than half lit. A solar eclipse happens when the Moon's shadow falls on Earth, and a lunar eclipse happens when the Moon moves into Earth's shadow.
Use Diagram 1 with the first two examples, Diagram 2 with the last one, and the eclipse table with Examples 3 and 4.
Physical model: one lamp, one ball, one head
In a dark room, a student holds a foam ball at arm's length. The LED lamp is the Sun and the student's head is Earth. The student turns slowly to the left (counterclockwise), keeping the ball in front of the face. With the ball toward the lamp, the student sees only its dark side. A quarter turn later, the right half of the ball is lit. With the lamp behind the student's head, the whole face of the ball is lit.
Result: The lamp always lights half of the ball. The phase changes because the student sees a different part of the lit half at each position: new moon, then first quarter, then full moon. No shadow of the head was needed for any of these shapes, so the shadow idea fails the test.
Graphical model: predicting phases on a calendar
The cycle from one new moon to the next takes about 29.5 days, so each quarter of the cycle takes about 29.5 ÷ 4 ≈ 7.4 days. A class sees a first quarter moon on the 4th of a 30-day month. When should they expect the next full moon, third quarter, new moon and first quarter?
Result: Full moon: 4 + 7.4 ≈ the 11th. Third quarter: 4 + 14.8 ≈ the 19th. New moon: 4 + 22.1 ≈ the 26th. Next first quarter: 4 + 29.5 = 33.5, which is about the 3rd or 4th of the next month.
Conceptual model: why solar eclipses are rare
The eclipse table below lists real eclipses from 2025 and 2026. Every solar eclipse falls on a new moon, but there are about 12 new moons a year and only a few solar eclipses. The Moon's orbit is tilted about 5° compared with Earth's orbit around the Sun.
Result: Because of the tilt, at most new moons the Moon passes a little above or below the line from the Sun to Earth, and its shadow misses Earth. An eclipse can happen only when a new moon (or a full moon) comes while the Moon is crossing Earth's orbit, which happens in two "eclipse seasons" a little less than 6 months apart.
Comparing lunar and solar eclipses
On March 14, 2025 the full moon passed through Earth's shadow, a total lunar eclipse, and it could be seen from the whole night side of Earth facing the Moon. On April 8, 2024 the Moon's shadow crossed Mexico, the United States and Canada, and the total solar eclipse could be seen only along a path roughly 200 km wide.
Result: Earth's shadow at the Moon's distance is much wider than the Moon, so the whole Moon can sit inside it and everyone who can see the Moon sees the eclipse. The Moon is smaller than Earth, so the dark center of its shadow covers only a small patch of Earth. During a total lunar eclipse the Moon often looks red, because a little sunlight bends through Earth's air into the shadow.
Model of the seasons: tilt, not distance
Earth's axis is tilted 23.4°, and it keeps pointing the same way in space as Earth orbits the Sun (Diagram 2). At the equinoxes the noon Sun's height above the horizon is 90° minus the latitude (how many degrees a place is north or south of the equator). At the June solstice add 23.4°, and at the December solstice subtract 23.4°. A town at 40° north latitude gets 50° at the equinoxes, 73.4° in June and 26.6° in December. Days there last about 15 hours in June and about 9 hours in December.
Result: In June the Northern Hemisphere is tilted toward the Sun: the Sun is higher, so its light is more concentrated, and it is up longer each day. Both effects bring more energy, so it is summer. Earth is actually closest to the Sun in early January, during northern winter, so distance does not cause the seasons.
Real eclipses, 2025-2026 (dates in Universal Time)
Date
Type of eclipse
Moon phase
March 14, 2025
Total lunar
Full
March 29, 2025
Partial solar
New
September 7, 2025
Total lunar
Full
September 21, 2025
Partial solar
New
February 17, 2026
Annular solar
New
March 3, 2026
Total lunar
Full
August 12, 2026
Total solar
New
August 28, 2026
Partial lunar
Full
Point out how to read the table. In an annular solar eclipse the Moon covers the middle of the Sun but leaves a bright ring, and in a partial eclipse only part is covered. Ask: "Which phase does every solar eclipse need? Every lunar eclipse? Do eclipses come one at a time or in groups?" Students should see that the eclipses come in pairs about two weeks apart, and that the pairs come in March, in September, then in February and March, then in August.
Guided Practice15 minutes
Pairs build a graphical model from a moon journal. A class recorded, by eye, how much of the Moon's face was lit on eight days after a new moon on day 0. Evening sightings were made after sunset and the waning moons were seen before school in the morning.
Moon journal (invented class data; percent lit estimated by eye to the nearest 5%)
Day
Percent of face lit
Lit side
2
5
Right
5
25
Right
8
55
Right
12
90
Right
15
100
Whole face
19
80
Left
22
50
Left
26
15
Left
Plot percent lit (vertical axis) against day (horizontal axis) and connect the points with a smooth curve. Label both axes.
Mark the day of the full moon and the two days when the face was about half lit. Name the phase on each of those days, using Diagram 1.
Extend the curve to predict the day of the next new moon and the next full moon. Explain how the 29.5-day cycle supports your prediction.
Explain why the lit side switches from right to left after the full moon, using the lamp-and-ball model in one or two sentences.
Expected results: the curve rises from 0% to 100% around day 15 and falls back toward 0% near day 29 or 30. The face is about half lit near day 7 or 8 (first quarter) and near day 22 (third quarter). The next full moon falls near day 15 + 29.5 ≈ 44. After the full moon the Moon has moved to the other side of its orbit, so we see its lit half from the other side.
Independent Practice10-15 minutes
Model critique cards. Each student draws one card: a moon phase, a solar eclipse, a lunar eclipse, or a season in one hemisphere. They draw a labeled model (Sun, Earth, Moon, light and shadow) that explains the event on the card, and add one prediction the model makes, such as the phase two weeks later or the season six months later. Students then trade cards with a partner, who checks three things: the Sun's light comes from one direction, the lit half of each body faces the Sun, and the prediction follows from the drawing. Partners write one question or correction on the back, and each student revises once.
Closure5 minutes
Return to the warm-up claim and vote: does the shadow idea pass or fail the test? Ask one student to show with the lamp and ball why a quarter moon needs no shadow. Exit ticket: "Today's model says it is winter in Chile while it is summer in Canada. In two sentences, use the tilt of Earth's axis to explain why." Look for answers that say the Southern Hemisphere is tilted away from the Sun at that time, so its sunlight is less direct and its days are shorter.
Differentiation Strategies
For Struggling Students
Give a phase sentence frame: "The Moon is at position ___ in its orbit. The Sun lights the side facing ___. From Earth we see ___ of the lit half, so the phase is ___."
Let students hold the ball and turn first, then draw, so the drawing records something they saw
Give a partly labeled copy of Diagram 1 with the light and dark halves already shaded
For Advanced Students
Ask students to use the eclipse table to predict the months of the next pair of eclipses after August 2026, and explain their reasoning
Have students explain, with a model, why the Moon rises about 50 minutes later each day (the Moon moves about 1/29.5 of the way around its orbit each day)
Ask students to use Diagram 2 to explain why the noon Sun is straight overhead at 23.4° north latitude on the June solstice
Assessment Guidance
What to Look For
Check that every drawing shows sunlight coming from one direction and the Sun-facing half of the Moon and Earth lit. Look for the shadow idea of phases, the idea that seasons come from Earth's distance to the Sun, and the idea that the Sun is "closer" to a hemisphere when it is tilted toward it. When students predict dates, check that they use the 29.5-day cycle and quarter steps of about 7.4 days. For eclipses, listen for the 5° tilt of the Moon's orbit as the reason eclipses are not monthly.
02
Classroom Activities
3 Activities
1
Lamp-and-Ball Moon and Eclipse Model
20 minGroups of 3
One student is Earth, one holds the lamp steady, and one records. The Earth student moves a foam-ball Moon around their head to make each phase, then lines the ball up to make both kinds of eclipse.
Procedure
Darken the room. Place the LED lamp at head height in the center, or one lamp per corner for several groups.
The Earth student holds the ball at arm's length and turns slowly to the left in 8 steps. The recorder sketches the lit shape the Earth student sees at each step and labels it with a phase name.
Solar eclipse: at the new moon position, move the ball until its shadow falls on the face of the recorder, who stands just behind the Earth student. Lunar eclipse: at the full moon position, move the ball into the shadow of the Earth student's head.
Now tilt the ball's path: hold the ball a little higher than the lamp on one side of the circle and a little lower on the other side, so it crosses lamp height at only two points. Try the two eclipses again.
Safety: use an LED lamp, which stays cool, tape the cord to the floor, and don't stare into the lamp. Walk, don't spin.
Discussion Questions
At which two positions could you make an eclipse, and which phase is each?
When the ball's path was tilted, why did most new moon and full moon positions give no eclipse?
The ball's shadow covered only part of the recorder's face, but the head's shadow could cover the whole ball. Which real eclipse does each one match?
Name one way this model is not like the real system (sizes, distances, the light source).
Modification for Distance Learning
Students use a lamp at home and an orange or a ball on a pencil, take a photo of each phase, and post a labeled set of eight photos.
2
Flashlight and Globe Seasons Lab
20 minPairs
Pairs measure how the same beam of light spreads out when it hits a surface at a low angle, then walk a tilted globe around a lamp to see why the angle of sunlight changes through the year.
Procedure
Tape graph paper to the desk. Hold a flashlight 20 cm from the paper, pointing straight down (90°), and trace the edge of the bright spot. Count the squares inside.
Keep the distance the same and tilt the flashlight so the beam meets the paper at 70°, 50° and 30°. Measure each angle with a protractor and trace and count again.
Then carry the globe around the lamp in a circle, keeping the axis pointed at the same wall the whole time. Stop at four places and observe where the light hits the Northern Hemisphere most directly.
Safety: never shine the flashlight into anyone's eyes.
Sample Data (invented)
At 90°, 70°, 50° and 30°, one pair counted 20, 22, 26 and 41 squares.
Discussion Questions
The flashlight gave out the same light every time. What happened to the light falling on each square as the angle got smaller?
In the sample data, the spot at 30° covered about twice as many squares as at 90°. What does that mean for the energy each square gets?
At which globe position did the light hit the Northern Hemisphere most directly? Which season is that for the Northern Hemisphere, and which for the Southern Hemisphere?
Challenge Variation
Pairs repeat the globe walk with the axis straight up (no tilt) and describe how the light on the Northern Hemisphere changes, or doesn't, around the circle.
3
Eclipse Season Detectives
20 minGroups of 3-4
Groups lay a moon calendar strip for 2025-2026 on a long sheet of paper, mark every full and new moon, and add the real eclipses from the table. They use the timeline, a graphical model, to find the pattern in when eclipses happen.
Procedure
Draw a timeline from March 2025 to September 2026, with one tick per week.
Starting from the full moon of March 14, 2025, mark a full moon every 29.5 days and a new moon halfway between each pair.
Mark the eight eclipses from the table in a second color.
Count the full moons from March 14, 2025 to September 7, 2025, and the days between them.
Expected Results
Every eclipse lands on a marked full or new moon. From March 14 to September 7, 2025 is 177 days, which is 6 cycles of 29.5 days (6 × 29.5 = 177). In each eclipse season a lunar and a solar eclipse are 14 to 16 days apart, half a cycle.
Discussion Questions
The timeline has about 38 new and full moons, but only 8 eclipses. Use the tilt of the Moon's orbit to explain why.
Why are the two eclipses in each pair about two weeks apart?
Use the timeline to predict the month of the next eclipse season after August 2026. How could you check your prediction?
Modification for Distance Learning
Groups build the timeline in a shared spreadsheet, with one row per week and a column for the phase.
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: Moon Phases in the Earth-Sun-Moon Model
A conceptual model seen from above the North Pole, not to scale. Sunlight comes from the left, so the left half of every Moon is lit. The Moon orbits counterclockwise. From Earth we see a different part of the lit half at each position, which gives the phase named next to it.
Diagram 2: Earth's Tilted Axis Through the Year
Earth's orbit seen at a slant, not to scale. The axis is tilted 23.4° and points the same way in space all year. At the June solstice the Northern Hemisphere is tilted toward the Sun; at the December solstice it is tilted away. At the equinoxes neither hemisphere is tilted toward the Sun.
04
Homework Assignment
~30 min
MS-ESS1-1 Homework: Using Models of the Earth-Sun-Moon System
Directions: Use the models from class (the lamp and ball, Diagram 1, Diagram 2, the flashlight data). The cycle of moon phases takes about 29.5 days. Eclipse dates are real dates in Universal Time; data marked invented are made up for practice. For every problem, include a labeled sketch of the model you used. Never look at the Sun, even through filters.
Part 1: Moon Phases and Eclipses (Problems 1-3)
A moon calendar for a 31-day month shows a full moon on the 9th. (a) Predict the dates of the next third quarter moon, new moon and full moon. (b) On which of your dates could a lunar eclipse happen, and on which could a solar eclipse happen? (c) Explain why an eclipse will probably not happen on those dates.
A student models phases by saying that Earth's shadow covers part of the Moon. (a) The Moon is sometimes a thin crescent in the evening sky just after sunset, close to where the Sun went down. Explain why the shadow model cannot explain this. (b) Draw the correct model for a crescent moon, with the Sun, Earth and Moon in place.
These are real eclipses from 2024: March 25 (penumbral lunar, meaning the Moon passed only through the pale outer part of Earth's shadow), April 8 (total solar), September 18 (partial lunar) and October 2 (annular solar). (a) Find the number of days between the two eclipses in each pair. (b) Find the number of days from April 8 to October 2 and how many moon cycles that is. (c) Use your answers and the tilt of the Moon's orbit to explain the pattern.
Part 2: Seasons (Problems 4-6)
A sky model gives these values for a town at 30° north latitude (invented data, rounded): noon Sun height 60° on March 20, 83° on June 21, 60° on September 22 and 37° on December 21; day length 12.1, 14.0, 12.1 and 10.2 hours on the same dates. (a) Graph both sets of data against the date. (b) On which date does the town get the most energy from the Sun? Give two reasons from the data. (c) Use Diagram 2 to explain the pattern.
Earth's distance from the Sun is about 147 million km in early January, 149 in early April, 152 in early July and 150 in early October. Average temperatures in those months are -4, 10, 24 and 12 °C in a city at 42° north latitude, and 21, 15, 10 and 15 °C in a city at 38° south latitude (invented data). (a) About what percent farther from the Sun is Earth in July than in January? (b) Graph both cities' temperatures by month, and describe how each one changes as Earth's distance changes. (c) A student says, "We have summer when Earth is closest to the Sun." Use the graph to write an argument for or against this claim.
Imagine Earth's axis were tilted 40° instead of 23.4°. (a) Use the rule from Example 5 to find the noon Sun height at the June solstice and the December solstice for a town at 40° north latitude. (b) Compare your answers with the real values for that town. Would its summers and winters be milder or more extreme? Explain with the flashlight model. (c) Describe how you would change the globe walk from class to test your prediction.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
Model
Sketch shows the Sun's light from one direction, the lit halves facing the Sun and correct positions
Sketch is present but a position, a label or the lit half is wrong
Use of the Model
Uses the model to explain or predict the pattern (phase, eclipse, season)
Describes the pattern without connecting it to the model
Data and Calculations
Dates, day counts and percents are correct and shown with work
Method is right but a value is wrong, or work is missing
Reasoning
Explains why with the 29.5-day cycle, the 5° tilt of the Moon's orbit or the tilt of Earth's axis
Reasoning is partly correct or relies on distance or shadows
05
Quiz: 20 Questions
Interactive, with answers
Instructions
Use the models from the lesson. The cycle of moon phases takes about 29.5 days, and Earth's axis is tilted 23.4°. Eclipse dates are real dates; data marked invented are made up for practice. 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
Which statement best explains why we see the Moon go through phases?
Answer: C
Half of the Moon is always lit by the Sun, and as the Moon orbits Earth we see more or less of that lit half. Choice A is the shadow idea: Earth's shadow reaches the Moon only during a lunar eclipse. Choice B is wrong because the Moon only reflects sunlight. Choice D is wrong because the Moon has almost no air and no clouds.
Question 2 of 20 · Multiple Choice
In the lamp-and-ball model, where must the ball be to show a full moon?
Answer: B
At full moon, Earth is between the Sun and the Moon, so the student sees the whole lit half when the lamp is behind the head. Choice A is the new moon position, where the student sees only the dark side. Choice C gives a quarter moon. Choice D ignores that the phase depends on the position.
Question 3 of 20 · Multiple Choice
There is a new moon on a Sunday. About how many days later is the third quarter moon?
Answer: A
New moon to third quarter is three quarters of the 29.5-day cycle: 3 × 29.5 ÷ 4 ≈ 22 days. Choice B is one quarter, which brings the first quarter moon. Choice C is half a cycle, which brings the full moon. Choice D is a whole cycle, which brings the next new moon.
Question 4 of 20 · Multiple Choice
During which phase can a lunar eclipse happen?
Answer: D
A lunar eclipse needs the Moon to move into Earth's shadow, which points away from the Sun, so Earth must be between the Sun and the Moon: a full moon. Choice A is when solar eclipses happen. Choices B and C are quarter moons, when the Moon is off to the side of Earth's shadow.
Question 5 of 20 · Multiple Choice
There is a new moon about every 29.5 days. Why isn't there a solar eclipse every month?
Answer: B
The Moon's orbit is tilted about 5° compared with Earth's orbit, so at most new moons the Moon passes above or below the Sun-Earth line and its shadow misses Earth. Choice A confuses brightness with alignment. Choice C is wrong because the Moon's shadow does reach Earth at every solar eclipse. Choice D is wrong because Earth's shadow points away from the Sun, toward the far side, not toward the new moon.
Question 6 of 20 · Multiple Choice
In the lamp-and-ball model, the foam ball is 5 cm wide and a student's head is about 18 cm wide. The real Moon is 3,474 km wide and Earth is 12,742 km wide. Which statement about the model is correct?
Answer: A
5 ÷ 18 ≈ 0.28 and 3,474 ÷ 12,742 ≈ 0.27, so the sizes match well. Choice B is wrong: the Moon is about 30 Earth widths away, so at this scale the ball would be about 30 × 18 cm ≈ 5.4 m from the head, not at arm's length. Choice C is wrong because the Sun is about 109 times as wide as Earth. Choice D is wrong because the class holds the ball at lamp height and tilts its path only in the last step, on purpose.
Question 7 of 20 · Multiple Choice
A total lunar eclipse happened on May 26, 2021. Using the 29.5-day cycle, on which date was a solar eclipse most likely?
Answer: C
The lunar eclipse was at full moon. Half a cycle later, about 26 + 14.8 ≈ 40.8, or June 10, came a new moon in the same eclipse season, and a solar eclipse did happen that day. Choice A adds only a quarter cycle (7 days), which gives a third quarter moon. Choice B adds a whole cycle and gives the next full moon. Choice D adds a whole cycle plus a quarter (about 37 days), which gives a third quarter moon.
Question 8 of 20 · Multiple Choice
What is the main cause of Earth's seasons?
Answer: D
The 23.4° tilt changes how directly sunlight hits each hemisphere and how long its days are over the year. Choice A is the distance idea; Earth is actually closest in early January, during northern winter. Choice B is wrong because the Sun's output barely changes over a year. Choice C is wrong because the Moon blocks sunlight only during rare solar eclipses.
Question 9 of 20 · Multiple Choice
Earth is about 147 million km from the Sun in early January and about 152 million km in early July. Which conclusion do these data support?
Answer: A
The Northern Hemisphere has winter in January, when Earth is closest to the Sun, so a small distance change cannot be what makes winter. Choice B reverses the data. Choice C is wrong: January is summer in the Southern Hemisphere. Choice D ignores the 5 million km difference in the data.
Question 10 of 20 · Multiple Choice
In a flashlight model (invented data), a beam held at 90° to the paper lights 12 squares. Tilted to 40°, the same beam lights 19 squares. About how much light does each square get at 40°, compared with 90°?
Answer: C
The same light is shared by 19 squares instead of 12, so each square gets 12 ÷ 19 ≈ 0.63, about 2/3 as much. This is why low winter sunlight warms the ground less. Choice A flips the ratio (19 ÷ 12 ≈ 1.6). Choice B forgets that the light is shared by more squares. Choice D divides the angles (40 ÷ 90 = 4/9) instead of comparing the areas.
Question 11 of 20 · Multiple Choice
Use the rule from the lesson. A town is at 45° north latitude. About how high is the noon Sun at the June solstice?
Answer: B
At the equinoxes the noon Sun is 90° - 45° = 45° high, and in June it is 23.4° higher: 45° + 23.4° ≈ 68°. Choice A subtracts the tilt, which gives the December height. Choice C is the equinox height. Choice D would happen only where the Sun is straight overhead, at 23.4° north.
Question 12 of 20 · Multiple Choice
It is late December. Where on Earth are the days longest?
Answer: D
In late December the Southern Hemisphere is tilted toward the Sun, so it has summer with long days. Southern Australia is in the Southern Hemisphere. Choice A has about 12-hour days all year. Choices B and C are tilted away from the Sun in December, so their days are short; near the North Pole the Sun does not rise at all.
Question 13 of 20 · Multiple Choice
A student's lamp-and-ball model makes an eclipse every time the ball reaches the new or full moon position. Which change makes the model match the real pattern better?
Answer: C
Tilting the path, as the Moon's orbit is tilted about 5°, makes the ball pass above or below the line to the lamp at most new and full moons, so eclipses happen only at a few positions. Choices A and D change the light, not the alignment. Choice B would make eclipses even easier to get.
Question 14 of 20 · Multiple Choice
Which list gives the phases in order, starting the day after a new moon?
Answer: A
After a new moon the lit part we see grows (waxes): a crescent, then half (first quarter), then more than half (gibbous), then full. Choice B lists the waxing phases backward. Choices C and D mix up the order and, in D, put a waning phase before the full moon.
Question 15 of 20 · Short Answer
In the early morning, before school, a student sees a Moon whose left half is lit. Name the phase, describe where the Moon is in its orbit, and predict about how many days until the next new moon.
It is a third quarter moon. The Moon is a quarter of the way around its orbit from the Sun-Earth line, after the full moon (the top of Diagram 1), so we see half of its lit half, on the left side. A new moon comes about a quarter cycle later: about 29.5 ÷ 4 ≈ 7 days.
Question 16 of 20 · Short Answer
A total lunar eclipse happened on March 3, 2026, at full moon. Predict the dates of the next two full moons, and explain whether either of them is likely to have a lunar eclipse.
Add 29.5 days for each cycle. March 3 + 29.5 days ≈ April 1 or 2, and March 3 + 59 days ≈ May 1. A lunar eclipse at either one is unlikely: eclipses happen only in eclipse seasons, when the Moon is crossing Earth's orbit, and the next season comes almost 6 months after March, around August. (The real eclipse table shows the next lunar eclipse on August 28, 2026.)
Question 17 of 20 · Short Answer
The total part of a lunar eclipse can last more than an hour. At any one town, the total part of a solar eclipse lasts only a few minutes (at most about 7 minutes). Use a sketch of the model to explain the difference.
During a lunar eclipse the Moon moves through Earth's shadow. Earth is about four times as wide as the Moon, so its shadow at the Moon's distance is much wider than the Moon, and the Moon takes a long time to cross the dark part. During a solar eclipse the dark center of the Moon's shadow is only a small spot on Earth, and it races across the surface as the Moon moves in its orbit, so it passes over any one town in a few minutes. The sketch should show the Sun, Earth and Moon in a line: the Moon inside Earth's wide shadow in one case, and the Moon's small shadow touching Earth in the other.
Question 18 of 20 · Short Answer
A student says, "It is summer in the Northern Hemisphere because that half of Earth is tilted closer to the Sun." Earth's radius is about 6,371 km and the Sun is about 150 million km away. Evaluate the claim and give a better explanation.
The claim is not supported. Tilting moves the Northern Hemisphere at most a few thousand km closer, and even 6,371 km is only about 6,371 ÷ 150,000,000 ≈ 0.004% of the distance to the Sun, far too small to matter. The better explanation: when the Northern Hemisphere is tilted toward the Sun, sunlight hits it more directly (the noon Sun is higher, so the same light falls on a smaller area) and the days are longer, so it gets more energy each day.
Question 19 of 20 · Short Answer
A class wants to observe the next partial solar eclipse from the schoolyard. Describe a safe way to observe it, and explain why the class's rule is to never look at the Sun, even through filters.
Sample answer: make a pinhole projector (a small hole in a card that casts an image of the Sun onto a second card or the ground), stand with your back to the Sun and look only at the projected image, or watch a live video stream. Looking at the Sun can permanently damage the eyes in seconds, even when part of it is covered, and a scratched, fake or wrongly used filter gives no warning, so the class never looks at the Sun at all.
Question 20 of 20 · Short Answer
Astronauts standing on the Moon during a total lunar eclipse look back at Earth. What do they see happen to the Sun? Use the Earth-sun-moon model to explain.
They see Earth block the Sun: for them it is a solar eclipse, with Earth covering the Sun. During a lunar eclipse the Sun, Earth and Moon are in a line with Earth in the middle, so from the Moon, Earth is directly in front of the Sun and its shadow falls on the astronauts. They might see a thin reddish ring of light around Earth, from sunlight bending through Earth's air, which is also why the Moon looks red from Earth.
0 of 20 answered · 0 correct
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Frequently Asked Questions
10 Questions
What does MS-ESS1-1 mean?
MS-ESS1-1 asks middle school students to build and use a model of the Earth, Sun and Moon to explain the repeating patterns of moon phases, solar and lunar eclipses, and seasons. The code stands for Middle School, Earth and Space Science, core idea 1 (Earth's Place in the Universe), performance expectation 1. The practice is modeling: students must use a model to explain and predict, not only name the phases.
Does MS-ESS1-1 have an assessment boundary?
No, MS-ESS1-1 has no Assessment Boundary. The Clarification Statement only says that models can be physical, graphical or conceptual. In practice, middle school lessons stay with patterns students can explain with a model, such as positions, light and shadow, and simple day counts. Orbit equations and gravity calculations are beyond this standard and come in high school (HS-ESS1-4).
What really causes the phases of the Moon?
Phases are caused by the changing angle from which we see the Moon's lit half as the Moon orbits Earth. The Sun always lights half of the Moon. At new moon that half faces away from us; at full moon it faces us; in between we see part of it. Earth's shadow is not involved, except during a lunar eclipse.
Why don't eclipses happen every month?
Because the Moon's orbit is tilted about 5° compared with Earth's orbit around the Sun. At most new and full moons the Moon passes a little above or below the line between the Sun and Earth, so no shadow lands on Earth or on the Moon. Eclipses happen in two eclipse seasons a little less than 6 months apart, when the Moon crosses Earth's orbit near a new or full moon.
What causes the seasons if it isn't Earth's distance from the Sun?
The tilt of Earth's axis causes the seasons. As Earth orbits, the hemisphere tilted toward the Sun gets more direct sunlight and longer days, so it has summer, while the other hemisphere has winter. Earth's distance changes only a little over the year, and Earth is closest to the Sun in early January, during northern winter.
How can students safely observe a solar eclipse?
Students should never look at the Sun, not even through filters, sunglasses or eclipse glasses, during class activities on this page. Safe options are a pinhole projector used with your back to the Sun, a colander or the gaps between leaves casting small images on the ground, or a live video stream. Teachers should check their school's own eclipse safety rules before any outdoor viewing.
What kinds of models count for MS-ESS1-1?
Physical, graphical and conceptual models all count, as the Clarification Statement says. A physical model is something students build or move, such as a lamp and a foam ball or a globe and a flashlight. A graphical model shows data, such as a moon journal graph or an eclipse timeline. A conceptual model is a labeled drawing or diagram that explains how the parts work together.
What mistakes do students make with Earth-sun-moon models?
Three frequent mistakes are explaining phases with Earth's shadow, explaining seasons with distance from the Sun, and drawing light coming from more than one direction. Another is lighting the side of the Moon that faces Earth instead of the side that faces the Sun. Asking students to use their model to make a prediction, and then checking it, brings these ideas to the surface.
Is MS-ESS1-1 taught in 6th, 7th or 8th grade?
It depends on the school. NGSS lists MS-ESS1-1 for grades 6-8 without assigning a grade, so states and districts place it in different years, often in a middle school Earth and space science unit. It is often taught together with MS-ESS1-2 on gravity and MS-ESS1-3 on the scale of the solar system.
What comes after MS-ESS1-1?
MS-ESS1-2 uses models of gravity to explain why the Moon and planets stay in orbit, and MS-ESS1-3 looks at the sizes and distances of solar system objects. In high school, HS-ESS1-4 uses mathematical models to predict the motion of orbiting objects, which is beyond this standard.
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Related Standards
5 standards
These standards connect to MS-ESS1-1: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
5-ESS1-2Prerequisite
Graph daily changes in shadows, day and night, and seasonal stars in the night sky
Lesson coming soon
1-ESS1-2Prerequisite
Relate the amount of daylight to the time of year
Lesson coming soon
Alongside
MS-ESS1-2Parallel
Model the role of gravity in the motions within galaxies and the solar system
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