Phases of the Moon: Why It Looks Different Every Night
5th grade · 45 min · Science
Objective. Students will name the eight phases of the Moon in order, explain that the changing appearance is caused by which side is lit by the Sun, and distinguish 'waxing' (illuminated portion increasing) from 'waning' (illuminated portion decreasing).
OverviewH+C
Most fifth graders have noticed the Moon changes shape but assume the Moon itself is changing — clouds in front, or the Moon shrinking and growing. This lesson untangles that misconception by anchoring the appearance change to a single fact: the Moon is always half-lit by the Sun, and we see different fractions of the lit half depending on where the Moon is in its orbit. Students model phases with a styrofoam ball and a flashlight, name them in order, and use the words waxing and waning correctly by exit ticket.
Lesson stepsH
Step 1 · 5 minAI-generated — review
Teacher: Show a time-lapse of the Moon over a month. Ask: 'What is changing — the Moon, or the way we see it?' Take 3-4 student answers without correcting yet.
Students: Watch the time-lapse. Share predictions about what is causing the Moon to look different each night.
Step 2 · 10 minAI-generated — review
Teacher: Teach the core idea: the Moon is always half-lit by the Sun. We see different fractions of that lit half because the Moon orbits Earth. Demonstrate with a flashlight and a ball at the front of the room.
Students: Watch the demonstration. Answer the check question: 'Is the Moon ever fully dark on its own?' (Answer: only the side facing away from the Sun.)
Step 3 · 18 minAI-generated — review
Teacher: Pair students. Give each pair a flashlight and ball-on-stick. Walk them through the eight phases in order, pausing at each so they can see the lit fraction change. Introduce 'waxing' and 'waning' at first quarter and third quarter respectively.
Students: Model each phase with the ball and flashlight. Label the phase strip in order. Discuss with partner whether the Moon is currently waxing or waning.
Step 4 · 7 minAI-generated — review
Teacher: Distribute the exit ticket: four unlabeled phase images. Students name each and mark waxing or waning. Collect.
Students: Complete the exit ticket independently.
Step 5 · 5 minAI-generated — review
Teacher: Quick share-out: ask which phase is happening tonight (look it up live). Send students out with the homework: observe and sketch the Moon for three nights this week.
Students: Note tonight's expected phase. Take home the observation log.