Discover Cause and Effect
Look at the world through your baby’s eyes. Respond patiently as they repeat an action and discover that what they do can make something happen.
- 4 months
- Quick prep
- At home
- About 5 minutes
Developmental benefits
- Cognitive：Responding when your baby repeats an action and drawing attention to what happens next helps them explore simple cause-and-effect relationships.
Preparation
What You’ll Need
- 1
A hand rattle
- 2
a toy that squeaks when pressed, such as a rubber duck
Step 1
The Bed Goes Thump
Between three and five months, your baby may lift their legs and thump them down on the mattress. This is a common movement, so you do not need to stop it when they seem comfortable. The action also creates an interesting result: kick, and the mattress goes “thump, thump.”
What to notice
- Lifts their legs and thumps them down on the mattress
Gross Motor - Makes an “ah” sound while kicking
Communicating and Speaking
Tips
- At another playful moment, hold your baby’s feet and gently repeat the kicking motion. Copy the sound so they can notice how the movement changes what they hear.
- If frequent kicking at night comes with waking or restless sleep, consider whether your baby may be using the movement to communicate a need.
- Notice your baby’s overall state when the kicking begins. If they look relaxed and happy, keep watching. If they seem uncomfortable or need something, respond to that cue.
Step 2
Tap a Toy on the Floor
During tummy time, your baby may suddenly tap a toy against the floor. Pick up another toy and join them. Copy the tapping sound and describe the result: “Tap! The toy made a sound.”
What to notice
- Repeatedly taps a toy against the floor
Exploration and Discovery - Pushes up on their forearms during tummy time Gross Motor
Tips
- If your baby has not tried tapping yet, demonstrate with your own toy and wait to see whether they copy the action.
- Place a mat beneath the toy if you want to soften the tapping sound.
- Use a few words to link the action with the result. Even before your baby understands every word, your description adds language to the shared experience.
Step 3
Make the Toy Sound
Offer a rattle or another toy that makes a sound through movement. If your baby only holds it, gently guide their hand through one shake, then wait to see whether they make the sound again. Show the same action with other simple sound-making toys.
What to notice
- Shakes a rattle repeatedly and listens to the sound Exploration and Discovery
- Watches a sound-making toy closely
Cognitive Self-Regulation (Executive Functioning)
Tips
- Whether you demonstrate or your baby makes the sound, name the action that caused it: “You squeezed the duck. Squeak!”
- Choose toys with a clear physical response, such as a rattle or squeaky duck, instead of toys that combine many strong lights and electronic sounds.
- Follow your baby’s attention during daily play. Describing what they act on and what happens next helps make the pattern easier to notice.
Better Parenting Content Team · Updated September 11, 2026