Rainy-day science experiments for curious preschoolers

Rainy afternoons can make the house feel small, especially when the children have already played with every toy in the cupboard. I have found that a simple science activity gives everyone something fresh to investigate without requiring a trip to the shops or a complicated clean-up.

These rainy-day science experiments for preschoolers use familiar household items such as water, ice, food colouring and bicarbonate of soda. They are designed for short attention spans, little hands and the kind of enthusiastic “what happens if…” thinking that makes early childhood so enjoyable.

Living in Australia means we can have very different weather from one day to the next. A wet Melbourne morning, a stormy Brisbane afternoon or a cool Sydney weekend can all become an opportunity to explore puddles, clouds, colour and movement indoors.

I share plenty of family activities and everyday parenting moments on Country Girl City Life, but these experiments are especially useful when screens have lost their appeal. The best part is that children learn through play, without feeling as though they are sitting through a lesson.

Make a rain cloud in a jar

Fill a clear glass or jar with water, then add a layer of shaving foam on top. Give your child a small cup of water tinted with a few drops of blue food colouring. Using a spoon or dropper, let them add the coloured water to the foam and watch it move down into the jar like rainfall.

Before starting, talk about how clouds hold tiny water droplets. When a cloud becomes full, the water falls as rain. Preschoolers will enjoy making predictions about whether the “rain” will arrive quickly or slowly, and the activity gives them an easy way to connect what they see in the jar with the wet weather outside.

Create a rainbow with water and light

A sunny window is helpful, but a torch can work on a cloudy day. Place a small mirror in a shallow bowl of water and angle it towards a wall. Shine the torch at the mirror and adjust it until a little rainbow appears. You may need to move the bowl or light several times before the colours show clearly.

Explain that white light contains many colours, and water can bend and separate that light. Preschoolers do not need the technical vocabulary to enjoy the discovery. Naming red, orange, yellow, green, blue and purple is enough for a satisfying colour hunt around the room.

Make a fizzy bicarbonate volcano

Place a few spoonfuls of bicarbonate of soda in a cup or small container set inside a tray. Add a little food colouring, then pour in vinegar and watch the bubbling reaction. A drop of washing-up liquid can make the foam last longer, although it is best to use a small amount to keep the clean-up manageable.

This activity is a favourite in our house because the reaction is immediate. I encourage the children to describe what they see rather than simply calling it “exploding”. Bubbles, fizzing, foam and overflowing are useful words, and children can test whether more vinegar creates a bigger eruption.

Explore what floats and sinks

Gather safe objects from around the home, such as a plastic lid, wooden spoon, toy block, cork, metal teaspoon and sponge. Fill a tub or washing-up bowl with water, then ask your child to guess whether each item will float or sink before placing it in the water.

Keep a simple two-column drawing nearby for their predictions and results. A rainy afternoon in an Australian home is a good time to use collected natural objects too, such as a smooth pebble or gum leaf, provided they are clean and safe. Talk about shape, weight and the material each item is made from.

Grow a bean in a clear cup

Line the inside of a clear cup with a damp paper towel and place a bean between the towel and the cup. Keep it somewhere warm with indirect light, checking it each day and adding a small amount of water when needed. Within several days, children may see a root appear, followed by a shoot.

This experiment teaches patience because the result is gradual rather than instant. Encourage your child to draw the bean each day or use a ruler to track its growth. It also provides a gentle way to discuss what plants need: water, air, warmth and light.

Investigate melting ice

Freeze small toys, leaves or coloured water in an ice cube tray. Place the frozen cubes in a tray and offer your child warm water, cool water and a little salt. They can use droppers or teaspoons to test which method melts the ice fastest.

Supervise closely and remind children that salt is for the experiment, not for tasting. Australian families will recognise this as an easy pantry activity, with ingredients available at supermarkets such as Coles, Woolworths or Aldi. If your child is still mouthing objects, use large, easily handled items and stay within arm’s reach.

Make a dancing cornflour mixture

Mix cornflour with water until it feels solid when pressed but flows when left alone. A good starting point is roughly two parts cornflour to one part water, adding small amounts until the texture feels right. Children can squeeze it, tap it and watch it slowly slide through their fingers.

This is a simple example of a non-Newtonian mixture, though preschoolers can focus on the surprising texture rather than the scientific label. Use a washable mat or tray, and keep the mixture away from drains because it can contribute to blockages. Australian household waste and plumbing systems are not designed for large amounts of paste being washed away.

Keep the discoveries safe and simple

Adult supervision matters for every activity involving water, small objects, food ingredients, glass containers or cleaning products. The Australian Children’s Education and Care Quality Authority places strong emphasis on supervision and safe environments through the National Quality Framework, and the same careful approach is sensible at home.

I prepare the tray before inviting the children over, tie back long hair and keep towels nearby. We also wash hands afterwards, particularly when using vinegar, food colouring or objects collected outdoors. The goal is curious play, so there is no need to force a result or correct every prediction.

A little mess is part of the fun, but boundaries make the afternoon calmer. We use washable clothing, protect the table and pack everything away together. When the rain clears, the children often continue the conversation by looking at puddles, wet leaves and clouds from the veranda.

Save a few jars, cardboard trays and plastic containers for the next wet-weather afternoon, then choose one experiment and let the children lead the investigation. With ordinary supplies and patient supervision, your kitchen table can become a small science lab full of fizz, colour and discovery.