## Balance and MotionThird Grade sCIENCE LESSON

Objective: Students will be able to explain the effects of balanced and unbalanced forces on the motion of an object. (Blooms – Applying)

I LOVE gymnastics, but some days I seem to have a big problem: I can't stay on the balance beam. When I walk across the beam, I begin to wobble back and forth and then fall to the ground. When I do flips, like you see above, I just can't seem to stay on! What might be my problem? Let's discuss what everyone thinks.

### Balance: a state of equilibrium

Class, can you think of a time when you have been in a situation where you could not balance?

Left Photo Source: https://www.flickr.com/photos/21042103@N03/3342173731 Right Photo Source:https://www.flickr.com/photos/21656109@N00/3784346530

This baby and the acrobats that we can see are both practicing their balance.

Now that we understand balance, let's take a look at a video that is going to teach us about motion too!

### Motion: the act or process of moving

At the beginning of the video, we learned about motion. Let's discuss what are some examples of motion?

"Earth" Image Source: https://pixabay.com/en/world-earth-planet-globe-spaceview-549425/

Each of these pictures share something in common: motion. Whether it is riding in a vehicle, moving your hands to put food in your mouth, climbing a rope, fishing for food, fire burning, or the natural, constant rotation of the planet earth, each of these is an act of motion. Now, what makes motion happen? We learned this in our video!

### Forces: a push or a pull

The force of the golf club moving fast pushes the golf ball to where it is desired to go. Can we think of some more examples we saw from our video about forces?

### Center of Gravity: the point around which mass is equally distributed

Class, let's all stand up! Lift one leg off of the ground, and let's see how well we can balance! How did you do?

If you were able to balance, your center of gravity was balanced (like this bird)! If not, this is because your center of gravity was lost when it strayed beyond the base of support, and gravity pulled you down! Here is a hint, the larger your base of support is, the greater stability you will have in balancing!

Now that we know about a force and the center of gravity, let's think about some balanced forces! Let's talk about some examples we can think of, and then we can look at some more examples I found!

Elephant image source: https://pixabay.com/en/elephant-sitting-plush-the-mascot-1678231/ Cat image source: https://www.flickr.com/photos/11337895@N00/27148560985 iPhone image source: https://www.flickr.com/photos/48126477@N05/10892564103 Girl image source: https://pixabay.com/en/sundress-summer-dress-girl-woman-336590/

What are some examples of unbalanced forces? Here's a hint - objects in motion! Let's discuss this as a class first. How about dropping our pencil? For sure! Falling off a bike is also an example of an unbalanced force.

### Now it is time for an activity!

2. Get into groups of 3-5 people
3. Each group will get a deck of cards!
4. With these cards, you will have 5 minutes to create a tower using only the playing cards. All cards do not need to be used.
Let's see who's tower is the tallest!

Let's read now about a girl in Paris who practices to be just like the high wirer artist she meets, and I want you to think about why this book is relative to our lesson today.

For your exit ticket, everyone will turn in a 3-2-1:

3 things you learned from today's lesson - 2 things you have a question about - 1 thing you want me to know!

#### Once you have completed this, we will spend the rest of the class time practicing with our balance and motion!

Log onto http://archive.fossweb.com/modulesK-2/BalanceandMotion/activities/rollercoaster.html to practice building your own roller coaster. For the roller coaster to work properly, you will need to remember it needs motion!

Credits:

Created with images by Tela Chhe - "Learning to Walk" • Jessie Pearl - "tight rope bike" • skeeze - "world earth planet" • Bob 4158 - "ADP-AHA Golf 210" • mybulldog - "Unknown" • MirelaSchenk - "elephant sitting plush" • spies, emanuele spies - "Sleeping beauty" • MattsMacintosh - "New iPhone/iPad mini stand" • Unsplash - "sundress summer dress girl" • Dave Peake - "Card Pyramid" • TeroVesalainen - "numbers 123 1"