3rd Grade Science Lesson

Tick, Tock, Swing & Rock: Predicting Patterns of Motion

Shared by A STEM Educator

3rd GradeNGSS Phenomenon-Based3-PS2-2, 3-PS2-145 min

Learning Objective

Students will be able to observe, describe, and predict patterns of motion (back-and-forth, spinning, up-and-down) by collecting timing data from pendulums of different lengths, identifying cause-and-effect relationships between string length and swing rate, and constructing evidence-based explanations of repeating motion.

Lesson Overview

Students investigate repeating patterns of motion using pendulums and everyday objects, building toward predicting future positions based on observed patterns. The anchor phenomenon of a grandfather clock's swinging pendulum drives inquiry into how motion can be measured, described, and predicted.

Materials

String cut to lengths: 10 cm, 20 cm, 30 cm, 40 cm (4 per group)
Small metal washers or pennies (3 per group) for pendulum bobs
Rulers and meter sticks
Stopwatches or timer app (1 per group)
Motion Sort Cards (printed — spinning, back-and-forth, up-and-down, non-repeating)
Recording sheets / investigation handouts
Tape or ring stand to hang pendulums
Short video clip of a grandfather clock pendulum swinging (for anchor phenomenon)
Whiteboard or chart paper for class data table
Colored markers

Scaffolded Task Progression

1Task 1

Motion Sort (Low-Floor): Your group has a set of Motion Cards showing everyday objects in action — a spinning top, a grandfather clock pendulum, a bouncing ball, a car driving straight, a yo-yo, a rolling wheel, a flag flapping in wind, and a leaf falling once. Sort the cards into two groups: Repeating Motion (the pattern keeps happening the same way) and Non-Repeating Motion (happens once or randomly). Record your two groups and write one sentence explaining how you decided.

2Task 2

Pendulum Observation (Developing): Build a pendulum using 20 cm of string and one washer. Hold the top of the string still and pull the washer about 5 cm to the side. Let it go and watch it swing. Draw the path the pendulum makes in the box below. Then answer:
(a) What type of motion is this?(b) Does the pendulum return to the same spot each time?(c) What do you predict will happen if you make the string longer?

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