How to Teach Balanced and Unbalanced Forces Experiments

Wondering how to teach balanced and unbalanced forces? Try these simple experiments. Your third or fourth grade students will have fun – and really get the concept.

Ms. Sanchez Prepares a New Science Unit

Our favorite third grade teacher sat at the back table with her teaching partner. “Let’s continue planning our science curriculum. Next up, balanced and unbalanced forces,” she said.

“Last year, I brought a wagon into the classroom. Then I had kids push and pull it from different directions. In the end, chaos broke out. Furthermore, my students didn’t really understand the concept.”

Mr. Jones shook his head and laughed. “I can just imagine that. But seriously, you’re overthinking it.”

“So how do you teach it?”

Mr. Jones flipped open his laptop and pulled up a file. “First,” he said, “we review the definition of a force. It’s just a push or pull.”

When you teach balanced and unbalanced forces, begin with a simple definition : a force is a push or pull.
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How to Teach Balanced Forces

“After we’ve established that,” Mr. Jones continued, “we experiment with some simple objects. I like to work on balanced forces first.”

He pointed to a worksheet on the screen. “This science unit has two options. You can give kids the worksheet and let them work independently. Or, if you’d like, it has prompts you can read aloud. With both options, kids work with simple, everyday objects. Let me rephrase that: small objects. No wagons needed.”

He placed an eraser on the table. “The first prompt asks kids to push on opposite sides with equal force.”

Mr. Jones put the pointer fingers of both hands on opposite sides of the eraser and pushed. “See? It doesn’t move.”

“Well, that’s easy,” Ms. Sneed said.

“Yep. Kids continue with two other small objects – like a pencil or paperclip. Then they draw conclusions about equal and opposite forces. In just a few minutes, they start to understand balanced and unbalanced forces.

“Next, they apply equal and opposite forces to moving objects. Of course, they find that the objects stay on course.”

To understand the difference between balanced and unbalanced forces, first ask kids to apply equal and opposite forces to small objects.

How to Teach Unbalance Forces

Mr. Jones scrolled to a new set of prompts. “Unbalanced forces take a little more effort. No pun intended. For stationary objects, they apply:

  • force from one side of the object but not the other
  • less force from one side of the object than the other
  • equal forces from opposite directions

“Kids find (1) when more force is applied to one side of a stationary object, it moves in the direction that the greater force was moving and (2) when equal but not opposite forces are applied, the object rotates.”

“Hmm, that’s interesting,” said Ms. Sneed.

“Finally,” Mr. Jones continued, “the students explore forces applied to moving objects. If a force is applied in the opposite direction that the object is moving, three things may happen:

  • If the force is less than the force of the moving object, the object will continue moving but slow down.
  • When the force is the same, the object will stop.
  • However, if the force is greater than that of the object, the object will move in the opposite direction.”

Ms. Sneed smiled. “This is great. So much learning for such simple activities!”

Mr. Jones nodded. “Right. The kids also experiment with two additional types of force on moving objects:

  • When a force is applied in the same direction that the object is moving, the object speeds up.
  • If a force is applied to the side of a moving object, the direction changes.”

“I definitely did not think this concept through,” said Ms. Sneed. “Now I see that our students need to explore a variety of situations with balanced and unbalanced forces.”

When teaching balanced and unbalanced forces, spend more time on unbalanced forces. They make objects move - and more!

Balanced or Unbalanced Forces?

“As the grand finale,” Mr. Jones said, “kids push on the wall. Of course, it doesn’t move. Does that mean that balanced forces are at play. We really debate this. In the end, I explain that the wall has its own force, called the normal force. Actually, it pushes back with the same force that’s applied.”

Ms. Sneed shook her head and laughed. “You learn something new every day!”

Then she frowned. “I don’t think one shot at these physical science activities will be enough. My students won’t remember the concepts of balanced and unbalanced forces when it’s time for standardized testing.

Practicing with Situations

Once again, Mr. Jones scrolled down in his file. That’s what’s great about this resource. After the experiments, kids practice with a series of situations. For example: Marco is pushing a wagon up a hill. His sister stands next to him and pushes in the same direction. What happens?”

“Haha!” said Ms. Sneed. “I knew there’d be a wagon somewhere in these balanced and unbalanced forces activities!”

Mr. Jones smiled. “Yep. You got your wish. And another one too: a test to wrap up the unit.”

“I really like this. Working with simple, everyday objects promises some seriously fun science.”

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