Third Grade Science Experiments (Page 35)

Paper DNA Model

STEM Activity

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Ever wondered how DNA, the genetic blueprint of a life-form, can encode and pass on the information on how to grow and maintain that life-form? Just like a cookbook contains a complete recipe for a dish, DNA stores the recipe for the life of an organism. Although each human has a unique DNA sequence, the DNA in all of us is about 99.9% identical! In this activity, you will make a model for a short section of DNA—enough to get a sense of what DNA is like and how it encodes life. Read more

Puzzle Fun with a Perimeter Magic Triangle

STEM Activity

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Do you ever use math as a tool to solve interesting problems? In the 1970s math was often taught with simple worksheets. One teacher developed an exciting way to learn math and logic; he developed what is now known as the perimeter magic triangle puzzles. Try them out—and have some fun as you start thinking about counting in a whole new way! Read more

Remove Silver Tarnish with a Homemade Battery

Science Fair Project Idea

Scientific Method

Have you ever wondered why silver jewelry that starts out nice and shiny turns brownish-black and dull over time? The brownish-black stuff is called silver tarnish, and it is the result of a chemical reaction on the silver's surface. Luckily, there are many ways to clean tarnished silver and make it shiny again! In this science project, you will explore how to clean tarnished silver using electrochemistry. The electrochemical silver cleaning reaction requires aluminum and a salt solution. Your… Read more

Robot, Make Me a Sandwich!

STEM Activity

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Have you ever wanted a robot assistant that could do all your household chores? Science fiction has been showing us such robots for decades, but they're still not available! What's taking so long? In this project you will investigate some of the challenges in programming a "robot" to do a simple household task, such as making a sandwich. Read more

Rocket Catcher Challenge

Science Fair Project Idea

Engineering Design Process

Inspired by real-world reusable rockets, in this engineering challenge, you will design and build a device to catch a falling rocket so it lands vertically. Drop the rocket from higher and higher heights to get a better score! The 2025 Science Buddies Engineering Challenge is over, but you can check out this page to see our other past engineering challenges and what this year's challenge will be! Teachers, lesson plan versions of this challenge are also available. Read more

Saturated Solutions: Measuring Solubility

Science Fair Project Idea

Scientific Method

Many essential chemical reactions and natural biochemical processes occur in liquid solutions, so understanding the chemical properties of liquid solutions is fundamentally important. This project asks the basic question, how much of a substance can dissolve in water, for three different substances: ordinary table salt, Epsom salts, and sugar. Read more

Simple Circuit Logic with Switches: An Electric Puzzle

Science Fair Project Idea

Scientific Method

Here's a puzzle you may have heard before which you can build as a simple electric circuit. First, the puzzle: a farmer is traveling to market with his cat, a chicken and some corn. He has to cross a river, and the only way to cross is in a small boat which can hold the farmer and just one of the three items he has with him. The problem is, he has to be very careful about what he chooses to leave behind at any time. If the cat and chicken are left alone, the cat will eat the chicken. If… Read more

Soil Color and Moisture

Science Fair Project Idea

Scientific Method

Have you ever taken a step onto what appeared to be dry ground, only to find yourself ankle-deep in mud? Yuck! When you walk through damp soil, it can be a very messy experience. How can you tell if soil is wet or dry before you step on it? In this science project, you will investigate whether the color of the soil can help you determine how dry or wet it is. Read more

Squishy Robots: Build an Air-Powered Soft Robotic Gripper

Science Fair Project Idea

Scientific Method

When you think about robots, chances are they are contraptions that you have seen on TV, in movies, or even in real life — and they are usually made of metal. What if you could make a soft robot that could bend, twist, or squirm like an octopus or an earthworm? Researchers at Harvard University have done exactly that, developing soft robots made of rubber and powered by air instead of electricity. In this project you will use their designs to build a soft robotic gripper of your own. Read more

Star light, Star bright: How Does Light Intensity Change with Distance?

Science Fair Project Idea

Scientific Method

Have you ever looked up at the stars at night and wondered how fast they were moving or how far away they were? By studying how the brightness of a star changes with distance, you can answer those questions. In this astronomy science project, you'll create a model of starlight and use a sensor app with your smartphone to discover the key relationship between brightness and distance. Read more

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