Warm Water

Have your preschooler sit still for a period of time, until he feels that he is cold or have him sit in a cool room with a short sleeve shirt. Once your preschooler feels cool or cold, have him go to a sink and turn his wrists over so that his palms are facing upward, exposing the arteries. Point out the arteries to your preschooler. Explain that arteries carry blood away from your heart. Then turn on warm to hot (but not burning hot) water and place your preschooler's wrists under the water. Your preschooler should begin to feel warmer in a few minutes. Why? This happens because you are heating up blood that is circulating in your body. This is the same reason why you drink hot liquids on cold days. A cup of hot cocoa will warm you from the inside out while the hot water will warm you from the outside in.

Body Movement

In the same way, have your preschooler sit still for about 30 minutes and become cool. Once your preschooler is cool or cold, ask him to jump up and down for 30 seconds. When your preschooler is done ask him if he feels warmer. If not, have him run in place for another 30 seconds. Ask again if you preschooler feels warmer. Eventually your preschooler's threshold will be reached and he will become warmer. Explain to your preschooler that movement makes us warmer because we are increasing the circulation of blood in our bodies by moving around. Increasing your circulation makes you warmer.

For more on how clothes make us warmer see Why Clothes and Blankets Keep Us Warm.

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Helpful Tips for Parents

• Connect science observations to real-world applications: "This is why bridges are built this way" or "This is how your body does that." Application makes science relevant.

• Record results with drawings or photographs. Scientists document — preschooler scientists should too. A simple science journal develops both literacy and scientific habit.

• Use correct scientific vocabulary from the start: observe, predict, experiment, hypothesis, result, evidence. Children absorb vocabulary in context without explicit teaching.

• Outdoor science (nature observation, weather tracking, garden study) is as rigorous as lab science and has the added benefit of physical activity and environmental connection.

Frequently Asked Questions

Should I explain the science behind experiments, or let children discover it?

Sequence matters enormously: always let children observe and wonder before explaining. "What do you notice?" and "Why do you think that happened?" should precede any explanation. If children ask why, give a simple, accurate answer — never give incorrect explanations to protect the mystery. After the child has observed and hypothesized, confirming or expanding their theory with correct information is appropriate and satisfying. Explaining first removes the inquiry that makes science learning durable.

How do I keep science learning going between experiments?

Science is a mindset, not a schedule. Keep a magnifying glass accessible for impromptu investigation. Ask "why do you think...?" during daily life. Notice scientific phenomena out loud: "Look at how steam rises from the soup — where does it go?" Maintain a simple nature observation area (a window bird feeder, a terrarium, a weather chart). The child who develops the habit of curiosity about the physical world is doing science continuously, not just during scheduled experiments.

Related reading: See also our science experiments at home and our nature walks guide for more ideas on this topic.

🎓 Skills Your Child Will Develop

• 🔍 Observation Skills — Paying close attention to what happens during an experiment — noting colors, textures, movements, and changes — builds the observational precision that all scientific and analytical work requires.
• 🔬 Scientific Method — Even a simple experiment teaches the predict-test-observe cycle that is the foundation of scientific thinking — and preschoolers who internalize this process approach problems with genuine scientific confidence.
• ⚖️ Cause & Effect Understanding — Seeing that one action reliably produces a specific result builds the logical framework children use in mathematics, reading (one event causes another in stories), and everyday reasoning.
• 💬 Science Vocabulary — Science introduces children to precise vocabulary — observe, predict, hypothesis, dissolve, absorb, transparent — that dramatically expands language range and supports the academic vocabulary children need in school.

Has your preschooler ever skinned his knee so badly that it is bloody? It may upset your preschooler to see the blood, but the blood coming out of the wound is a good thing. It helps clean out the wound. You then put a bandage on it and some antibacterial cream and it heals in no time. The healing qualities of blood are just one it's purposes in our body. Blood is also the basis for our body's temperature control. Your preschooler is likely not aware of how much blood moves through his body. Here are two experiments that will make your preschooler more aware of one of the main purposes of blood in our body--temperature control. It will also teach your preschooler how to warm up quickly when he is cold.