中文（繁體）
中文（简体）
English
Pupils usually say the seasons come from Earth going round the Sun, and that the Moon changes shape because of Earth shadow. This lesson replaces both causes: seasons come from the tilted axis, and phases come from the angle at which we see the lit half.
Objectives — By the end the pupil can: (1) explain day and night with one rotation in 24 hours and 15 degrees per hour, and say why Hong Kong has daylight while the other half of Earth is dark; (2) explain the seasons with a tilted axis plus orbit, say why summer days are longer, and state that distance from the Sun is not the cause; (3) order new moon, first quarter, full moon and last quarter, give about 29.5 days for the cycle, and separate a solar from a lunar eclipse by asking which body blocks which.
01 Prerequisites (3-minute check)
If any of these fails, fix it before the lesson starts.
| Skill | Quick check | Pass mark |
|---|---|---|
| Watching day and night | How does the Sun move across the sky in one day? | Rises in the east, highest at noon, sets in the west |
| A year and its months | How many months and roughly how many days in a year? | 12 months, about 365 days |
| Light travels straight | What happens when light meets something opaque? | It is blocked and a shadow forms behind |
02 Lesson flow (45 minutes)
| Time | Stage | Tutor does | Student does |
|---|---|---|---|
| 0-5 min | Diagnose | Ask why we have seasons and write the answers on the board unedited | Say the reason out loud |
| 5-12 min | Rotation and time zones | Demonstrate with a globe and torch, mark the lit and dark halves | Point to Hong Kong on the globe |
| 12-22 min | Three acts | Teach day and night, then seasons, then phases; ask for one repeat each time | Repeat the axis tilt gives longer summer days |
| 22-30 min | Order the phases | Give eight phase cards to arrange with reasons | Order them and say phases are 3 to 4 days apart |
| 30-38 min | Eclipses | Use three balls and move the Moon to see where the shadow falls | Say Moon blocks Sun against Earth blocks Moon |
| 38-45 min | Exit check | Collect three answers and mark at once | Name which step went wrong |
03 Teaching script (read it out)
Scene 1: Rotation and day: 24 hours, 15 degrees an hour
Put a globe on the desk and hold a torch as the Sun. Before turning anything, ask which half is lit and which is dark, then turn the globe slowly and let the pupil watch Hong Kong go from dark to light and back to dark.
Give two numbers: one rotation takes 24 hours and a full turn is 360 degrees, so the globe turns 15 degrees every hour. Hong Kong has roughly twelve hours between sunrise and sunset, which is half a turn. That is why Hong Kong has daylight while the opposite side of Earth is in darkness.
Clear one persistent confusion out loud: the Sun does not travel round Earth. Earth turns, and the Sun only appears to rise in the east because Earth turns towards the east.
Close with one sentence from the pupil: Earth turns by itself, and the side facing the Sun has day.
Give two numbers: one rotation takes 24 hours and a full turn is 360 degrees, so the globe turns 15 degrees every hour. Hong Kong has roughly twelve hours between sunrise and sunset, which is half a turn. That is why Hong Kong has daylight while the opposite side of Earth is in darkness.
Clear one persistent confusion out loud: the Sun does not travel round Earth. Earth turns, and the Sun only appears to rise in the east because Earth turns towards the east.
Close with one sentence from the pupil: Earth turns by itself, and the side facing the Sun has day.
One rotation takes 24 hours, and the side facing the Sun has day.
Scene 2: Orbit and seasons: a tilted axis, not distance
Keep the same torch and walk the globe around it, but keep the axis tilted the same way the whole time. Do not straighten it.
Stop and look: when the northern half leans towards the Sun, sunlight strikes more directly and the day is longer, which is summer. Half an orbit later the northern half leans away, the light is slanted and the day is shorter, which is winter. So the seasons come from leaning towards or away from the Sun, not from being nearer or further.
Give two numbers: one orbit takes about 365 days, and each of the four seasons lasts roughly 91 days. Ask the pupil to point to where Hong Kong is in January and again in July.
If the pupil still says summer means Earth is closer, ask what season Australia has at the same moment. The answer is opposite, and distance cannot explain opposite.
Stop and look: when the northern half leans towards the Sun, sunlight strikes more directly and the day is longer, which is summer. Half an orbit later the northern half leans away, the light is slanted and the day is shorter, which is winter. So the seasons come from leaning towards or away from the Sun, not from being nearer or further.
Give two numbers: one orbit takes about 365 days, and each of the four seasons lasts roughly 91 days. Ask the pupil to point to where Hong Kong is in January and again in July.
If the pupil still says summer means Earth is closer, ask what season Australia has at the same moment. The answer is opposite, and distance cannot explain opposite.
Seasons come from the tilted axis, and the two hemispheres have opposite seasons.
Scene 3: Eight phases: the lit half never changes, our angle does
Break the commonest error first: phases are not caused by Earth shadow. Earth shadow only reaches the Moon during a lunar eclipse.
Half of the Moon is always lit by the Sun. As the Moon goes round Earth we see different amounts of that lit half: nothing at new moon, the right half at first quarter, the whole disc at full moon, the left half at last quarter.
Give two numbers: the Moon takes about 27.3 days to go round Earth, but about 29.5 days from one new moon to the next, because Earth also moves round the Sun and the Moon has to catch up. Eight phases therefore sit about 3.7 days apart.
Finish with eclipses: when the Moon comes between the Sun and Earth it blocks the Sun, which is a solar eclipse; when Earth comes between the Sun and the Moon its shadow falls on the Moon, which is a lunar eclipse. One line separates them: the Moon blocks in a solar eclipse, Earth blocks in a lunar eclipse.
Half of the Moon is always lit by the Sun. As the Moon goes round Earth we see different amounts of that lit half: nothing at new moon, the right half at first quarter, the whole disc at full moon, the left half at last quarter.
Give two numbers: the Moon takes about 27.3 days to go round Earth, but about 29.5 days from one new moon to the next, because Earth also moves round the Sun and the Moon has to catch up. Eight phases therefore sit about 3.7 days apart.
Finish with eclipses: when the Moon comes between the Sun and Earth it blocks the Sun, which is a solar eclipse; when Earth comes between the Sun and the Moon its shadow falls on the Moon, which is a lunar eclipse. One line separates them: the Moon blocks in a solar eclipse, Earth blocks in a lunar eclipse.
Phases change because our viewing angle changes, not because of Earth shadow.
04 Question types and worked steps
| Type | Example | Steps | Answer |
|---|---|---|---|
| Day and night reasoning | It is noon in Hong Kong; what time is it on the opposite side of Earth | Use the longitude difference to get the time gap, then ask lit or dark | About midnight, because that side faces away from the Sun |
| Explaining seasons | Why is July hotter than January in Hong Kong | Name the tilt first, then the angle of sunlight and length of day | The northern half leans towards the Sun, so light is more direct and days are longer |
| Ordering phases | Put new moon, first quarter, full moon and last quarter in order | Start where nothing is visible, increase the lit fraction, then decrease | New, first quarter, full, last quarter |
| Naming an eclipse | The Moon moves into Earth shadow; what is this called | Ask who blocks whom, then which body is blocked | A lunar eclipse, Earth blocks the light reaching the Moon |
Sanity check (teach this): Reasonableness check: one rotation is 24 hours, so an answer of 12 hours for a full cycle has halved the turn. If a pupil says summer happens because Earth is nearest the Sun, the opposite seasons in the two hemispheres refute it at once. Giving 27.3 days for the phase cycle confuses the sidereal month with the synodic month, and two dates of new moon settle it. A solar eclipse can only happen by day and a lunar eclipse only by night, so an evening solar eclipse is a reversal. The Moon is much nearer than the Sun, which is why a small Moon can cover a huge Sun; that does not contradict the Sun being larger.
05 Independent practice (3 questions)
| Question | Answer | What to watch |
|---|---|---|
| Day and night | How long is one rotation, and how many degrees per hour | Answer 24 hours and 15 degrees, and say the lit side has day |
| Seasons | Hong Kong has winter in January; what season does Australia have, and why | Summer, because the southern half is leaning towards the Sun |
| Phases | It is full moon today; roughly when is the next full moon | About 29 to 30 days, and name that period the synodic month |
06 Common mistakes and what to say
| Mistake | Student writes | Say this |
|---|---|---|
| Seasons as distance | Writes that summer comes because Earth moves closer to the Sun | Look at the globe: the axis stays tilted. In July the northern half leans towards the Sun, so it is hot; at the same moment Australia has winter, and distance cannot explain that. |
| Phases as Earth shadow | Writes that the Moon is hidden by Earth shadow, which is why we sometimes cannot see it | Earth shadow only reaches the Moon during a lunar eclipse. On an ordinary night we see no moonlight because the lit half faces away from us. |
| Rotation and orbit mixed | Writes that one trip round the Sun takes a day | One trip round the Sun is a year, 365 days. One turn on its own axis is a day, 24 hours. |
| Eclipses reversed | Writes that a lunar eclipse is the Moon blocking the Sun | Who blocks whom? Moon blocking the Sun is a solar eclipse, by day. Earth blocking the Moon is a lunar eclipse, at night. |
07 Homework (paper, section and question numbers)
- Primary 5 General Studies paper, Section C Science and Technology — Section C: Earth movement and moon phase questions, marked against the answer sheet
- Primary 5 General Studies paper, Section D Charts and data — Section D: read a table of daylight hours and describe the seasonal change
- Primary General Studies chapter index — Revise the weather and natural hazards chapter to link daylight with seasons
08 Exit check (last 5 minutes)
| Question | Answer | Decision |
|---|---|---|
| How long is one rotation, and where does day come from | 24 hours, and the side facing the Sun has day | Answering 12 hours means half a turn was counted, so redo the globe demonstration |
| Why do we have seasons | A tilted axis plus orbit, changing the angle of light and the length of day | Answering distance means the cause was not replaced; retell the opposite hemispheres |
| About how long from new moon to the next full moon | About 15 days, within a cycle of about 29.5 days | Answering 27.3 days means the sidereal month was used; reteach the two periods |
09 Tutor FAQ
Do we need the ecliptic plane and the 23.5 degree tilt?
At Primary 5 the phrase the axis is tilted is enough; the number belongs to secondary school. A number without the opposite-seasons consequence teaches nothing.
Must the phases be shown with objects?
A torch and a small ball are enough, and the pupil should turn them personally. Watching the lit part change beats memorising eight names from a diagram.
Are eclipses examined?
Primary 5 General Studies asks for recognition and explanation, not calculation. Who blocks whom, and day or night, is sufficient.
Find a tutor — freeTutor Registration →
A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.