Rainy Day Projects

Homemade Density Column in a Jar

Your child measures and carefully pours four liquids — honey, dish soap, colored water, and cooking oil — into a tall clear jar, one at a time, to build a column where each liquid floats on the one below it. The column stays separated as long as it is not shaken, and small objects dropped in sink to different levels depending on their own density. This is a patient, observational experiment that suits the 8–10 age band well: it rewards care, generates genuine predictions, and produces something to look at and discuss.

Ages
8–10
Time
40 min
Adult help
Light adult help
Mess
Low mess

Before you start

Before calling your child over, find the tallest clear jar you own — a large pasta sauce jar or a pint mason jar works well. Measure out each liquid into a separate small cup so pouring is controlled. The honey goes in first; it is thick and slow. Dish soap goes second and needs to be poured gently down the inside of the tilted jar. Colored water goes third — one drop of food coloring is enough, and warn your child it stains fingers. Cooking oil goes last. The most common stall is impatience: if poured too fast, layers mix and take ten minutes to re-separate. Encourage your child to pour down the side of the jar, not straight down the center. Wind down by dropping small household objects — a grape, a small button, a piece of foil — and predicting which layer each one will settle in.

You will need

  • Tall clear jarA large pasta sauce jar or pint mason jar
  • HoneyAbout three tablespoons; dark honey shows layers most clearly
  • Dish soapAbout three tablespoons; a contrasting color to the honey helps
  • WaterAbout three tablespoons
  • Food coloringOne drop in the water only

    Food coloring stains skin; use a single drop, not a squirt, and rinse fingers quickly if they get colored.

  • Cooking oilAbout three tablespoons; vegetable or canola oil both work
  • Small household objects to drop inoptionalA grape, a small button, a piece of crumpled foil
  • Four small cupsTo pre-measure each liquid before pouring

Steps

  1. 1

    Measure liquids into cups

    Have your child measure about three tablespoons of each liquid into its own small cup. Add one drop of food coloring to the water cup and stir. Remind them that the order of pouring matters — ask which liquid they think is heaviest and will sink to the bottom.

  2. 2

    Pour honey into the jar

    Pour the honey in first, directly down the center. Tilt the jar so it coats the bottom evenly. Let it settle for a minute before the next pour — honey is slow and needs time to level out.

    Tip: Warm the honey jar briefly in hot water if it is very thick and hard to pour.

  3. 3

    Add dish soap slowly

    Tilt the jar slightly and pour the dish soap down the inside wall, not straight down the center. It should settle as a distinct layer on top of the honey. Pouring slowly along the glass wall reduces mixing.

    Tip: If the layers mix, wait five minutes — they will re-separate on their own.

  4. 4

    Pour in the colored water

    Again, tilt the jar and pour the colored water slowly down the inside wall. Ask your child to watch carefully for the moment the water meets the soap layer. It should float on top without mixing if poured gently enough.

  5. 5

    Add the oil layer last

    Pour the cooking oil down the side of the jar last. It will float immediately above the water, completing the four-layer column. Hold the jar up to a window or lamp to see the layers clearly and let your child describe what they see.

  6. 6

    Drop objects in and predict

    If you have small objects ready, have your child predict which layer each one will settle in before dropping it. Drop them in one at a time and observe. Ask: 'Why do you think the grape stopped there and not higher up?' Connect the answer back to the liquid layers.

    Tip: A grape typically sinks to the soap-honey boundary; a small piece of crumpled foil usually sinks to the bottom.

  7. 7

    Discuss what density means

    Ask your child to rank the liquids from heaviest to lightest based on where they settled. Introduce the word 'density' as the word scientists use for how much stuff is packed into the same amount of space. Honey has more packed in than oil, so it sinks below it.

Try it another way

  • Add a fifth layer — rubbing alcohol poured very gently — above the oil, which floats on oil and extends the column for older or more patient children.
  • Two children can each build their own column and compare whether their layers separated as cleanly, discussing what they did differently.
  • After observing the settled column, put a lid on the jar and shake it gently, then watch over the next twenty minutes as the layers slowly re-separate.

Keep in mind

  • Food coloring stains fabric and takes several washes to leave skin; keep it away from clothes and wipe spills immediately.

What they get out of it

Children learn that liquids have different densities — how much is packed into a given space — and that denser liquids sink below lighter ones no matter what order you pour them in.

Take it to the table

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