Safety first (please read):
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— Adult supervision required for any experiment involving flame, hot glass/metal, or small parts.
— Keep a bucket of water, a metal tray, or a fire extinguisher nearby for
candle experiments.
— Do experiments on a stable surface, away from curtains, papers, or anything
flammable.
— If you want to avoid flame, use battery tealights / hairdryer / hot water
alternatives I note below.
1) Tethered “Hovering Cup” — hot-air / convection demo
Materials: 1 light paper cup (not plastic), 1 small candle or
LED tealight, 2 thin wooden sticks (skewers), string/twine, metal tray.
Steps:
- Put the candle
in center of metal tray. Light it (adult lights).
- Tape the two
wooden sticks as a cross over the rim of the cup so they act as a little
scaffold for the cup to rest on (cup open side down). Tie a short piece of
string to the center of the scaffold so cup is slightly tethered.
- Hold the cup
15–20 cm above the candle with the string (adult holds). Don’t let the cup
touch the flame.
- Watch as the
warmed air under the cup produces lift—the cup may wobble and rise a
little while tethered; do not release it into the open air.
What happens (science): Warm air is less dense and rises (convection). The upward flow of warm air can produce a small lifting force under a lightweight cup.
Safety: Use a paper cup (plastic will melt). Keep the cup tethered and don’t release it. Replace open flame with a battery tealight for a much safer demo (same convection idea but milder).
Difficulty/Time: Easy, 5–10 minutes.
2) Candle + Jar Oxygen Test (candle uses up oxygen)
Materials: 1 small candle on a plate, clear glass jar or drinking
glass, water, food coloring (optional).
Steps:
- Fill the plate
with a thin ring of water (add a drop of food coloring so it’s visible).
Light the candle.
- Place the jar
upside down over the candle and onto the plate so the rim sits in the
water.
- Watch: the flame
goes out and water level inside the jar rises.
What happens: The candle consumes oxygen inside the jar; when oxygen level drops, flame goes out. Cooling and reduced gas (and partial CO₂) cause the water level to rise as internal pressure changes.
Safety: Adult lights the candle. Do this on a non-flammable plate and away from drafts.
Difficulty/Time: Very easy, 5–7 minutes.
3) Fireproof Balloon (water absorbs heat)
Materials: 1 balloon, water, candle or lighter (adult).
Steps:
- Fill the balloon
about halfway with water and tie it. The result is a water-filled bulb.
- Have an adult
light the candle and gently hold the balloon with the water side down
above the flame briefly.
- The balloon will
touch the flame but not pop (for a while) because the water inside draws
away heat.
What happens: Water absorbs heat from the flame so the rubber never reaches its melting point at the contact point.
Safety: Still dangerous if left too long — the balloon can still burst. Keep flame brief, do it over a sink or metal tray, and adult must be in control. Battery tealight is a safer option to demonstrate heat transfer using a hair dryer (hot air) instead.
Difficulty/Time: Easy, 3–5 minutes.
4) Dancing Raisins (CO₂ bubbles lift raisins)
Materials: Clear glass, clear soda (e.g., Sprite), a few raisins.
Steps:
- Fill the glass
with soda. Drop in 3–5 raisins.
- Watch — after a
short time, bubbles form on the raisins, and raisins float up and then
sink again repeatedly.
What happens: Carbon dioxide bubbles from the soda attach to the rough raisin surface, making them buoyant; when bubbles pop at the surface, raisins sink again.
Safety: No flame, kid-safe.
Difficulty/Time: Very easy, 2–10 minutes.
5) Pepper Scatter — surface tension + soap effect
Materials: Shallow bowl, water, ground black pepper, dish soap.
Steps:
- Fill the bowl
with water. Sprinkle pepper evenly across the surface.
- Dip a finger
with a little dish soap and touch the center of the water. The pepper will
instantly rush to the edges.
What happens: Pepper floats due to surface tension. Soap reduces surface tension locally; water pulls away from that spot, carrying pepper with it.
Safety: Kid-safe. Clean hands after.
Difficulty/Time: Very easy, 1–2 minutes.
6) Walking Water (capillary action & color mixing)
Materials: 3 or 4 clear glasses, water, food coloring (different
colors), paper towels.
Steps:
- Line up glasses
and fill every other one halfway with water. Add different food colors to
those glasses. Leave the empty ones between the colored glasses.
- Fold paper
towels into strips, place one end in a colored glass and the other end in
the empty glass next to it. Repeat for each gap so water has a paper towel
path.
- Wait 15–30
minutes: colored water “walks” to the empty glass and colors mix.
What happens: Capillary action pulls water along the paper towel; the empty glass fills and colors mix, demonstrating movement of water and diffusion.
Safety: Kid-safe.
Difficulty/Time: Easy, 20–40 minutes.
7) Layered Density Rainbow (salt/sugar water density)
Materials: Tall clear glass or jar, water, sugar, food coloring
(different colors), spoon.
Steps:
- Prepare three
solutions: heavy (very sweet — 4 tbsp sugar + small water), medium (2 tbsp
sugar), light (no sugar). Color each differently.
- Very gently pour
the heaviest (most sugar) solution into the bottom of the glass. Then
carefully pour the medium over the back of a spoon so it flows slowly onto
the heavy layer; finally add the lightest.
- If done gently,
layers stay separate and you get visible colored strata.
What happens: Denser liquids stay below lighter ones because of different densities.
Safety: Kid-safe; adult helps with pouring for best effect.
Difficulty/Time: Moderate patience, 10–20 minutes.
8) Mini Lava Lamp (oil, water, and fizz)
Materials: Clear plastic bottle or jar, water, vegetable oil, food
coloring, Alka-Seltzer tablet (or baking soda + vinegar small amount).
Steps:
- Fill jar 1/3
with water, then top up with oil leaving space. Water sinks below oil.
- Add a few drops
of food coloring (it drops through oil into the water). Break an
Alka-Seltzer tablet into pieces and drop one piece into the jar. Watch
colored blobs rise and fall.
What happens: Alka-Seltzer makes CO₂ bubbles that grab colored water and carry it up through the oil; when bubbles pop, the water blobs fall back.
Safety: No flame, kid-safe. Do it in a tray if it might spill.
Difficulty/Time: Easy, 5–10 minutes.
9) Bending Water with Static (balloon or comb)
Materials: Balloon (or plastic comb), running tap (thin stream).
Steps:
- Rub the balloon
vigorously on hair or sweater for 20–30 sec to charge it.
- Turn tap to a
thin steady stream of water. Slowly bring the charged balloon near the
stream (without touching). The stream will bend toward the balloon.
What happens: Rubbing transfers electrons to the balloon, creating static charge. The charged object attracts the polar water molecules, bending the stream.
Safety: Kid-safe and very visual.
Difficulty/Time: Very easy, 2–5 minutes.
10) Invisible Ink & Reveal (lemon juice + heat)
Materials: Lemon, water, cotton swab or thin paintbrush, white paper,
candle or hair dryer (adult).
Steps:
- Squeeze lemon
into a bowl and mix a little water. Dip a cotton swab and write a message
on white paper; let it dry completely — the message becomes invisible.
- To reveal,
either gently hold the paper near a warm lamp or have an adult hold it
near (not in) a candle flame; or use a hair dryer to warm it. The hidden
writing will brown and appear.
What happens: Lemon juice is mildly acidic and weakens the paper fibers; when heated, the writing oxidizes and browns faster than the paper.
Safety: Use a hair dryer or LN (low flame) controlled by an adult. Don’t put paper into flame.
Difficulty/Time: Easy, 5–10 minutes plus drying.
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