Third Grade STEM Activities for Kids (223 results)

How Big Are the Planets in Our Solar System?

STEM Activity

143 reviews

Did you know that there are more planets than stars in our galaxy? All of these planets circle around a star, but only eight of them—Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune—circle around the Sun—the star in our solar system. This activity explores the relative size of these eight planets. Is one bigger than the others, or are they all about the same size? Read more

How to Grow the Best Crystals

STEM Activity

130 reviews

Have you ever wondered how crystals are made? Crystals come in all different shapes and sizes. However, the purest and cleanest crystals are usually also the ones that grow to be the largest in size. In this activity, you will compare the size and shape of crystals grown at different temperatures. With just water and Borax, a household cleaning product, you can discover the method for growing large, pure crystals! Read more

Hydroponics Made Easy

STEM Activity

139 reviews

Do you think plants can grow without soil? If you've tried growing vegetables, you probably planted the seeds or seedlings in soil. Soil gives the plants the nutrients they need to grow. However, plants can grow without soil, too, using a process called hydroponics. In this activity, you will transform a bottle into a mini-garden that needs only light, air, and nutrient-rich water to grow! Read more

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Make String from Algae

STEM Activity

215 reviews

Did you know that the seaweed you've seen in the ocean or even eaten as a snack is inspiring innovators to imagine new materials? Large brown algae, like kelp, contains polymers—long chains of molecules—that are more environmentally friendly than the ones in most plastics. These natural polymers (alginates) could eventually be used to create sustainable everyday objects. Try your hand at using a bit of chemistry to turn biodegradable polymers from algae into your own custom… Read more

Make Tie-Dye T-shirts with Permanent Markers

STEM Activity

24 reviews

Have you ever made a tie-dyed t-shirt? It can be a lot of fun to dye a shirt in bright colors with spiraling designs (especially when it is done on a warm day outside to prevent indoor messes)! In this science activity, you will get to dye a t-shirt with your own colorful artwork using permanent markers. Along the way, you will find out how solubility helps your drawings leave beautiful designs on the fabric. Read more

Blowing the Best Bubbles

STEM Activity

42 reviews

If you have ever tried to make bubbles using plain water, you may have seen that it does not work. This is because the surface tension of water is too high. When detergent is added to water, it lowers the surface tension so that bubbles can form. Other things can be added to this mixture, such as corn syrup or glycerin, to make a solution that is even better for creating bubbles. In this science activity, you will find out which solution creates the best bubbles! Read more

Build an Archimedes Screw

STEM Activity

80 reviews

The Archimedes screw is an ancient device used to lift water from one location to another. They are so useful that they are still in widespread use today! After a quick trip to the hardware store, you can build your own Archimedes screw in this fun activity. Read more

Make a Kazoo

STEM Activity

43 reviews

Do you remember your last parade, party, or fair? You might have been surrounded by sounds of all kinds: fireworks, music, and, maybe even the famous (or infamous) sound of kazoos. A kazoo is a very simple musical instrument, made up of a hollow pipe with a hole in it. They may be simple, but these little noisemakers are a great way to explore sound. In this activity you'll be investigating how kazoos work by building your own! Read more

Make a Milk Rainbow

STEM Activity

133 reviews

Have you ever seen a rainbow after a rainfall, or drawn a rainbow for fun? They can be fun to make using colorful markers or other craft supplies. But did you know you can actually make a simple rainbow using milk, liquid detergent (i.e., soap), and food coloring? How the rainbow is created by this mixture might surprise you! In this science activity, you will make your own milk rainbow and explore how detergent and surface tension are involved in its creation. Read more

Making Shadow Puppets

STEM Activity

85 reviews

Have you ever played with your own shadow? It is fascinating how it follows your every move. But why do you not see your shadow every day? Why is your shadow very long sometimes, and other times very short? In this activity, you will make your own shadow puppet and explore how you can change the shape or size of its shadow. If you like, you can even create your own shadow play! Read more

Model Your Blood Flow

STEM Activity

65 reviews

Why is it important to eat healthy and exercise? If you don't, you might end up with a cardiovascular disease. These diseases are conditions that affect your heart and blood vessels. The job of your cardiovascular system is to transport blood through your heart, veins, and arteries, to provide oxygen and nutrients to your body. If this blood flow doesn't work properly anymore, it can have serious consequences. In this activity, you will find out what happens to the blood flow of people that… Read more

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