1-ESS1-2: Daylight and Seasons – How the Amount of Daylight Changes Through the Year

General Overview

Performance Expectation – 1-ESS1-2: Make observations at different times of year to relate the amount of daylight to the time of year.

Clarification Statement: Emphasis is on relative comparisons of the amount of daylight in the wintaer to the amount in the spring or fall.

Assessment Boundary: Assessment is limited to relative amounts of daylight, not quantifying the hours or time of daylight.

“Why does it get dark so early in winter?” and “Why is it still light outside when we’re eating dinner in summer?” are questions children have asked for as long as humans have existed. 1-ESS1-2 takes these everyday observations and turns them into a formal scientific investigation: students collect data on daylight at different times of year and discover one of the most reliable and ancient patterns in all of nature – the annual cycle of changing day length.

This standard is distinguished by one of its most important design features: it requires observations at multiple points in time across the school year. It cannot be taught fully in a single week or even a single month. A student who only observes daylight in December has one data point; a student who compares December to September and March has a dataset that reveals a pattern. This longitudinal requirement mirrors exactly how climatologists, ecologists, and astronomers work – returning to the same measurement protocol at regular intervals to track change over time. This makes 1-ESS1-2 one of the most authentically scientific investigations in all of elementary school.

The science and engineering practice is Planning and Carrying Out Investigations: students make systematic observations at different times of year with the explicit purpose of comparing them. The crosscutting concept is Patterns: seasonal patterns of sunrise and sunset can be observed, described, and predicted. The disciplinary core idea is ESS1.B (Earth and the Solar System): “Seasonal patterns of sunrise and sunset can be observed, described, and predicted.”

Critically, this standard does not require students to explain why daylight varies with the seasons. The cause – Earth’s axial tilt and the changing angle of sunlight across the year – is a complex three-dimensional spatial relationship that most students are not cognitively ready to model until Grade 5 or later. What Grade 1 students are developmentally ready for is the observation: more daylight in summer, less in winter, spring and fall in between, and this pattern repeats year after year. “Discovery before explanation” is excellent pedagogy. Students who have genuinely documented and wondered about seasonal daylight will be far more motivated and prepared to understand its cause when the mechanism is finally introduced.

The connection to 1-ESS1-1 is direct and powerful: students who have tracked the sun’s daily arc discover through 1-ESS1-2 that the arc itself changes across seasons – higher and longer in summer (many daylight hours), lower and shorter in winter (few daylight hours). The shadow investigation bridges these two standards: noon shadows traced in September and December reveal dramatically different sun heights without any verbal explanation being necessary.

Scope and Sequence

What Comes Before (Kindergarten and Earlier in Grade 1)

In kindergarten, students tracked daily weather patterns (K-ESS2-1) and observed how sunlight warms Earth’s surface (K-PS3-1). Earlier in Grade 1, students investigated the sun’s daily pattern across the sky and shadow behavior (1-ESS1-1). These experiences establish two important foundations: students are comfortable making regular sky observations, and they understand that the sun’s position in the sky affects the amount and intensity of light and warmth reaching Earth’s surface. 1-ESS1-2 extends the timescale of observation from a single day to a full year, making the annual cycle of daylight visible through student-collected longitudinal data.

At This Grade Level (Grade 1)

Students make at least two observations at different times of year – ideally in fall, winter, and spring – that allow meaningful comparison of daylight amounts. They observe qualitatively that in winter, darkness comes much earlier in the evening and the morning sky is dark at school arrival time; in spring, the reverse is true. They connect this to the shadow observations from 1-ESS1-1: noon shadows are longest in winter (sun lowest) and shortest in summer (sun highest). The key Grade 1 learning outcomes are:

1. Winter has less daylight than fall or spring.
2. Summer has the most daylight of any season.
3. This pattern is consistent and predictable year after year.
4. Changes in daylight can be observed through sunrise and sunset times, the quality of light during certain hours, and the height and length of shadows.

What Comes After

In Grade 5 (5-ESS1-2), students formally represent data on daily changes in shadow length and direction in graphical displays, revealing patterns that connect directly to both 1-ESS1-1 and 1-ESS1-2. They are also introduced to Earth’s axial tilt as the mechanism causing seasonal variation in daylight and temperature. In Middle School (MS-ESS1-1), students develop and use models of the Earth-sun system to quantitatively explain seasons, calculating daylight hours at different latitudes and times of year. In High School, students analyze solar energy data across seasons, model the planetary energy budget, and evaluate the implications of Earth’s axial tilt for climate, biodiversity, and human civilization. The Grade 1 foundation – “there is more daylight in summer than winter, and this follows a pattern” – is the observational bedrock for all of this later understanding.

What Students Must Understand

The Core Annual Pattern

The amount of daylight – the number of hours between sunrise and sunset – changes throughout the year in a consistent, predictable, repeating pattern. In the Northern Hemisphere (where all US students are located), the pattern is: winter has the least daylight of any season, summer has the most, and fall and spring have intermediate amounts. The transition is gradual – daylight increases slowly from the winter solstice through spring and summer, then decreases from summer through fall and back to winter. The pattern is the same every year without exception. This means we can predict with confidence: next December will have short days; next June will have long days. This predictability connects 1-ESS1-2 directly to the crosscutting concept of Patterns and to the science and engineering practice of using patterns for prediction.

What Daylight Changes Look Like in Daily Life

Students must make the connection between the abstract concept of “more or less daylight” and their concrete daily experiences. In winter: it is dark when many students arrive at school; it becomes dark shortly after school ends; outdoor play after school may happen in dimming light or darkness. In summer: the sun rises before most students wake up; it is still fully light at dinnertime; stars don’t appear until well into the evening. In fall and spring: the morning light is moderate; it is usually still light at the end of the school day but gets dark in the early evening. These personal, experiential reference points make the data meaningful and personally relevant – a critical feature of effective science learning for young children.

The Connection Between Daylight, Shadow, and Sun Height

Students who have traced noon shadows in different seasons discover that winter noon shadows are dramatically longer than fall or spring shadows at the same time of day. This physical observation proves that the winter sun is lower in the sky at noon than the fall or spring sun – and a lower sun means less time above the horizon, which means fewer daylight hours. This cross-standard connection is one of the most elegant in all of Grade 1 science: the shadow investigation from 1-ESS1-1 becomes direct evidence for the seasonal daylight pattern of 1-ESS1-2. Students do not need to understand the causal mechanism (axial tilt); the connection between low sun = long shadows = short days is itself a powerful pattern-level understanding.

The Solstices and Equinoxes (Conceptual Introduction)

Students should know that there is one day each year when the days are longest (around June 21, the summer solstice) and one day when they are shortest (around December 21, the winter solstice). There are also two days when day and night are approximately equal (around March 21 and September 21, the equinoxes). Students are not required to know the precise dates, scientific names, or mechanisms – but being aware that these “turning points” exist, and experiencing them through class observation (going outside at 4 PM in December and noting the darkness; observing the late evening light in June if school extends there), makes the annual pattern concrete and personally memorable.

What Students Do NOT Need to Understand at This Level

The cause of seasonal daylight variation (Earth’s axial tilt – taught in Grade 5); precise hour counts of daylight; the formal terms “solstice” and “equinox” (though they can be introduced as vocabulary if students show readiness); the difference between Northern and Southern Hemisphere seasonal patterns; why daylight saving time shifts sunset times on clocks (this is a human convention, not an astronomical reality).

Key Vocabulary

Daylight, darkness, sunrise, sunset, season, winter, spring, summer, fall/autumn, pattern, predict, observation, longer, shorter, more, fewer, compare, annual, year, solstice (enrichment), equinox (enrichment).

Lesson Ideas and Activities

Activity 1: The Year-Long Daylight Tracker (Core Ongoing Investigation)

This is the primary investigation for 1-ESS1-2 and must run throughout the entire school year. Beginning in September, students answer two questions every school day: (1) “Was it light or dark when you came to school this morning?” and (2) “Was it light or dark when you got home yesterday afternoon?” Record responses on a large class tracking chart with one row per week and columns for Light/Dark at arrival and departure. At the end of each month, tally: “How many days was it dark in the morning this month? How many days was it dark when we got home? How does this month compare to last month?” Create a simple monthly comparison display visible on the classroom wall. The most powerful instructional moments arrive naturally: in late November when students first start noting that it is now dark at arrival; in December when darkness comes at around 4:30 PM; in January when students start noticing the morning is light again; and in March when they compare directly to December. This investigation requires no equipment, no materials beyond a wall chart and markers, and costs nothing – yet it produces genuine longitudinal scientific data that first graders collect themselves.

Activity 2: Seasonal Sunrise and Sunset Time Cards

On or near the first day of each season (approximately September 23, December 21, March 21, and June 21), look up the official sunrise and sunset times for your city from a reliable source (timeanddate.com, the US Naval Observatory, or weather.gov). Display these as large seasonal time cards posted side by side on the classroom wall. Students observe and compare: “In December, the sun set at 4:30. In June, the sun set at 8:15. When was it darker earlier? Which month had more hours of daylight?” The math connection is natural: which number is larger – 4:30 or 8:15? By how much? Even without calculating exact hours, students can compare times and draw clear conclusions. This activity also introduces the idea that the sun’s daily schedule is not fixed – it changes gradually every day, though the change is small enough to notice only across weeks and months.

Activity 3: Seasonal Noon Shadow Comparison

Using the same fixed object and location established for the 1-ESS1-1 shadow investigation, repeat the noon shadow measurement at the start of each season. Take photographs with a meter stick for scale and create a side-by-side display: “Our Noon Shadow on October 1 vs. December 21 vs. March 21.” The December shadow will be dramatically longer than the October or March shadow – sometimes three to five times longer depending on latitude. Students immediately perceive this difference without any numbers or calculations. The discussion questions write themselves: “Which shadow is longer? What does that tell us about where the sun was in the sky? If the sun is lower in December, does it stay in the sky for more or less time? So which day had more daylight – October or December?” This cross-standard investigation is one of the most convincing empirical demonstrations of seasonal daylight change available to first-grade teachers.

Activity 4: “When Does It Get Dark?” Family Investigation

Assign students a recurring homework task: once each week for one full month, note with their family approximately what time the sun sets. Do this investigation in late fall (October–November) when the change in sunset time is most dramatic – sunset moves approximately 2–3 minutes earlier per day in October in most US locations. Students bring back their weekly data, and the class plots it on a large graph: Week 1 sunset time, Week 2, Week 3, Week 4. Students observe the line clearly trending downward (sunset getting earlier each week). Discuss: “What pattern do we see? What do you predict sunset will be in December? In June?” This activity connects classroom science to real family experience, involves families as scientific partners, and produces a compelling graphical dataset that students have personally generated.

Activity 5: Seasonal Sky Photos – Which Season Is This?

Collect (or take) four photographs of the sky or outdoor scenery taken at exactly the same time of day – for example, 5:00 PM – in each of the four seasons. In December, the 5:00 PM sky is completely dark. In June, the 5:00 PM sky is bright blue. In September and March, the sky is intermediate – late golden light or early twilight. Present these four photographs to students in random order and ask: “Can you put these in order from the season with the most daylight to the season with the least? How can you tell which season each photograph was taken in? What clues are you using?” Students practice evidence-based reasoning, pattern recognition, and seasonal comparison simultaneously. For enrichment, add photographs of the same outdoor location in each season – students can observe not just sky brightness but also snow cover, leaf color, and other seasonal markers alongside the light quality.

Activity 6: Solstice Events – Making the Pattern Tangible

Mark the winter solstice (~December 21) and spring equinox (~March 21) with brief class events that make the astronomical moment personally memorable. Winter solstice event: On or near December 21, go outside at 4:00 PM together to experience the darkening sky. Discuss: “Today is the shortest day of the year – it has the least daylight of any day. But here’s the amazing thing: after today, the days will start getting longer again!” Spring equinox event: On or near March 21, go outside at sunset time and observe: “Today, day and night are almost equal. Remember how dark our days were in December? Look how different it is now!” Compare the class tracking chart data from December to today. Making astronomical events personally experiential – going outside, feeling the quality of the light, comparing with a remembered earlier experience – is far more powerful than any chart or video.

Activity 7: Living Things and Seasonal Daylight – Cross-Curricular Connections

Discuss how the seasonal change in daylight affects living things around students: plants bloom when days get longer in spring because increasing daylight triggers flowering hormones; some birds migrate south in fall as days shorten and return in spring as days lengthen; hibernating animals enter dormancy as fall daylight decreases and emerge as spring daylight increases; trees drop leaves in fall as days shorten and leaf out in spring as days lengthen. Read a picture book connecting seasonal change to plant or animal behavior (“The Seasons of Arnold’s Apple Tree” by Gail Gibbons; “When Winter Comes” by Nancy Van Laan; “Owl Moon” by Jane Yolen). Ask: “How is the amount of daylight like a signal to plants and animals? What would happen to a migratory bird if it couldn’t tell what season it was?” This cross-disciplinary connection helps students see that seasonal daylight patterns are not merely academic – they are the organizing rhythm of the living world.

Common Student Misconceptions

Misconception 1: “Cold weather causes short days.”

Students commonly reverse the cause-and-effect relationship, believing that cold temperatures cause short days rather than understanding that both cold temperatures and short days are consequences of the same underlying pattern (the sun’s lower path in winter). This matters because it places the student’s explanatory framework entirely in the wrong direction. Address it by asking: “Which comes first – the short day or the cold temperature? If we could make a winter day longer by turning on a giant lamp, would the temperature automatically go up?” Establish the sequence: the sun’s path changes (it is lower and shorter in winter), which changes how much daylight there is AND how much total solar energy reaches Earth’s surface, which affects temperature. Both short days and cold temperatures are effects of the same seasonal pattern, not causes of each other.

Misconception 2: “Seasons are caused by Earth moving closer to and farther from the sun.”

This is the most common astronomical misconception among both children and adults globally, and it is intuitive: you might expect summer to be when Earth is closest to the sun (making it hotter) and winter when it is farthest. In reality, Earth is actually slightly closer to the sun in January (Northern Hemisphere winter) than in July (Northern Hemisphere summer). At Grade 1, this standard does not require teaching the cause of seasons – do not teach the correct mechanism yet, but also do not reinforce the incorrect one. If students offer the “closer to the sun” explanation, respond: “That’s a really reasonable guess – it makes a lot of sense! But scientists discovered something surprising about this. We’ll learn about it when we’re a bit older. For now, let’s focus on the pattern we can observe: more daylight in summer, less in winter.”

Misconception 3: “Daylight saving time is why there is more daylight in summer.”

Students (and many adults) confuse the human convention of daylight saving time – which shifts the clock to move daylight to later in the evening – with the actual astronomical reality of longer days in summer. Daylight saving time does not create extra daylight; it simply rearranges when that daylight falls relative to our clock. The same amount of astronomical daylight exists with or without clock changes. Address this directly if it comes up: “Daylight saving time is something people invented to shift when the day’s light shows up on our clocks – it’s like a trick we play on ourselves. But the real reason summer days have more total light is something happening in space – not something we can change by moving our clocks.”

Misconception 4: “The sun always rises at 6:00 AM and sets at 6:00 PM.”

Children who have been told that a “full day” is 12 hours of day and 12 hours of night may believe these times are fixed. In reality, only at the equinoxes (twice per year) is the day approximately 12 hours long. In most of the US, December sunrise can be as late as 7:30–8:00 AM and sunset as early as 4:15–4:30 PM. In June, sunrise can be as early as 5:15 AM and sunset as late as 8:30–9:00 PM. The entire 1-ESS1-2 investigation empirically refutes this misconception – when students actually track sunrise and sunset times across the year, the dramatic variation is impossible to ignore. Real data is far more convincing than any correction through explanation.

Misconception 5: “All places on Earth have the same amount of daylight.”

Students may generalize from their own experience and assume that the seasonal daylight pattern they observe is universal and identical everywhere. In reality, the variation in day length increases dramatically with latitude – locations near the equator have nearly equal day and night year-round, while locations near the poles can have 20+ hours of daylight in summer and as few as 2–3 hours in winter. The continental US has significant variation: Miami, Florida has approximately 10.5 hours of daylight in December, while Anchorage, Alaska has approximately 5.5 hours. This “wonder” can be raised without requiring students to understand the mechanism: “If you had a cousin in Alaska, would they see the same amount of daylight as us in December? Scientists have found something amazing – places farther north have even shorter winter days and even longer summer days. We’ll learn why someday!”

Misconception 6: “Every day in summer is the same length.”

Students who understand that summer days are “longer” as a general category may not realize that day length changes every single day of the year – very slowly near the solstices (when the sun’s path barely changes from day to day) and more quickly near the equinoxes (when the daily change is most rapid, up to 2–3 minutes per day in the US). The ongoing daily tracking in Activity 1 reveals this gradual, continuous change. Ask students: “Did the sun set at exactly the same time every day this week? Let’s check our data.” Students will find small daily differences that add up to large seasonal differences – an important insight into how gradual change produces dramatic effects over time.

Misconception 7: “More daylight means it will be warmer that same day.”

Students sometimes assume that the day with the most daylight (June solstice, ~June 21) will be the hottest day of the year. In reality, the hottest days of summer typically occur in late July or early August – weeks after the solstice – because the land and oceans take time to absorb and radiate the extra solar energy. This “lag” between maximum daylight and maximum temperature is called the “seasonal lag” or “thermal lag.” At Grade 1, this is enrichment territory, but it is worth mentioning if students make this connection: “You’re right that more daylight means more solar energy reaching Earth! But the land and water take time to warm up from all that extra energy – so the hottest days actually come a few weeks after the longest day. It’s like how an oven takes time to heat up even after you turn it on.”

Assessment Questions

Observation and Data Reading

1. Look at our seasonal daylight chart. In which month did it get dark earliest after school? In which month did it stay light the longest? How do you know from the data?
2. In which season is it usually dark when you arrive at school? In which season is it still light when you go home in the evening?
3. Here are four pictures of the outdoor sky, each taken at 5:00 PM in a different season. Can you put them in order from the season with the most daylight to the one with the least? What clues did you use?
4. Our noon shadow in December was much longer than our noon shadow in September. What does that tell you about where the sun was in the sky in December compared to September?

Pattern Recognition and Prediction

5. We have observed that December has the least daylight of any month we measured. What do you predict about how much daylight next December will have? Why are you confident in that prediction?
6. It is March and we have noticed the days are getting longer. Based on this pattern, what do you predict about the days in April? In June? Why?
7. A student says “I have no idea when the sun will set tonight.” You have your class daylight tracking chart. How could you use our data to make a reasonable prediction?
8. We only collected data in fall, winter, and spring. What do you predict our summer data would show? Why do you think so?

Comparison and Relative Amounts

9. In September, sunset was around 7:00 PM. In December, sunset was around 4:30 PM. Was there more daylight in September or December? How much earlier did it get dark in December? How do you know?
10. Which season had the most daylight in our observations? Which had the least? What was in between? Can you put all four seasons in order from least daylight to most?
11. Compare our class tracking chart from October to our chart from January. What changed? What does this tell us about the pattern of daylight through the year?

Evidence-Based Reasoning and Real-World Application

12. A student says “Days and nights are always exactly the same length – 12 hours each.” What evidence from our investigations would you use to show this is incorrect?
13. Why do you think farmers throughout history needed to know about the pattern of daylight through the year? How might knowing that spring days are getting longer help them decide when to plant crops?
14. If you were planning an outdoor after-school event for your class, which time of year would be easiest – December or May? Why? What does daylight have to do with your answer?
15. We noticed that some birds flew away in the fall and came back in the spring. How might the amount of daylight be connected to when birds migrate? What pattern might the birds be responding to?
16. Draw a picture showing what the sky looks like outside your window at 5:00 PM in winter and 5:00 PM in summer. Label each drawing with the season. What is different between the two pictures? What does this show about daylight and the seasons?