# STEM Lab: Investigating Balance

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## Objective

SWBAT complete the first step of the engineering design process--think-- about balance in the force and motion unit.

#### Big Idea

Does everything balance? What can you put on each side of a balance scale to make them balance?

## Teacher Preparation

This is the first of several lessons that take place over a week. My students spend one week each month in our STEM lab (science, technology, engineering, and math) and the lessons follow the engineering design cycle. On the first day, the students think about the problem or concept, which is often researching and building their background knowledge so that they are prepared to build something to solve a problem or conduct an investigation. This lesson could also be taught as a stand-alone lesson as an investigation of balance.

In North Carolina, we teach the Essential Standards. This lesson aligns to 1.P.1.3, 'Predict the effect of a given force on the motion of an object, including balanced forces'. My essential questions today come from the students themselves during the warm up, and I refer back to them in the wrap up. Click here to hear my Explanation of Essential Standards.

Materials:

*1 balance scale per 2 students

*A large variety of small objects of different weights that students can use in the balance scales

*1 Think about Balance Recording Sheet per student (plus extras!)

## Warm Up

5 minutes

To get my students excited about balance and also to provide a quick review of force and motion, I show this video. The video shows a dinghy race, acrobats, a tight-rope walker, a squirrel, a parrot, and the camera itself - all  amazing real-world examples of balance that amaze me --and my students! Using media to provide examples supports Science and Engineering Practice 8, Obtaining, Evaluating, and Communicating Information by using media to obtain scientific information to determine evidence about the natural and designed world.

After my students are excited about balance, I say,

"Today, we are going to start the STEM design cycle by thinking about balance! Turn your partner and explain how the examples in the video showed balance. What is a scientific question you have about balance?"

I list 2 of their questions on the board, making sure to include 'How can I make objects balance?' as one of them! Asking scientific questions supports Science and Engineering Practice 1, Asking Questions and Defining Problems as students in K-2 ask questions based on observations to find out more information about the natural and the designed worlds.

## Think

35 minutes

To further engage students in thinking about balance, they are going to investigate using balance scales and many different objects. To ensure that they are focused and remain on task, and also to make sure that they remember what they learn, I say,

"To think more deeply about balance, you are going to use a balance scale and some object to conduct an investigation to see what you can learn with your partner. While you work, you need to record what you discover on this recording sheet".

I show the recording sheet on the SmartBoard so the students can see exactly how to complete it. I say,

"This is how you use a balance scale. You are your partner have to work together. Choose 1 object at a time, and put 1 object in each side. Watch as I demonstrate. If I put a rock in this side, and a feather in this side, what happens? That's right - the side with the rock goes down because it's....heavier! That's correct. Well, if it is heavier, is the scale balanced? No! How could I make it balance?"

Before I set my students off on their investigation, I want them to truly understand what it is that they are doing - otherwise, they are simply putting objects in a box and watching it move. They must understand what they are doing, so the modeling is crucial to the activity. I go through the example and then I return to the recording sheet and I use the SmartBoard to actually model filling my example out.

"So to make my balance scale balance, I chose to remove the rock and change that side to a piece of paper, which made the scale balance - both sides had an equal amount of weight so the scale was not heavier on one side or the other. Now, on my recording sheet, I need to draw as accurately as possible what was in each side and then label each side".

After I have modeled the activity, I have students collect their materials including the balance scales and objects and recording sheets, and work with their STEM lab partners that are predetermined for this week. I choose partners based on how well students work together - and with a large class in a small space, that is really important!

As the students settle in to work, I go around and engage in conversations, furthering them asking things like "Why do you think that didn't balance?" and "What could you add to that side to make it balance?" About 10 minutes in to the investigation, I stop the class. I say,

"Some of you have thought of this, but I want to give you something else to try. What if instead of having just one object on one side, you tried two? It might be harder because there are more combinations that could work, but you can try it. Remember, though, one your recording sheet to draw and label both objects."

Conducting an investigation collaboratively to produce data to serve as the basis for evidence to answer a question supports Science and Engineering Practice 3, Planning and Carrying Out Investigations.

Then, after our time is up for today with about 5 minutes left in the class, I stop the activity and ask my students to clean up and get ready for the wrap up section.

## Wrap Up

5 minutes

To end the lesson, I ask students,

"Who would like to share a combination that you were able to make balance?"

As students share, I show their work on the document camera and comment on their accurate drawings and labeling to model the purpose of scientific recording for sharing with peers. Communicating information supports Science and Engineering Practice 8, including both orally and written ideas and drawings that provide detail about scientific ideas, practices, and design ideas.

Then I say,

"Who can answer our questions that we wrote at the beginning of class? Turn to a partner and see if you can each answer one!"

Giving students time to answer these questions is important, so I choose to do this with their partner instead of as a whole group. We are also going to continue with the design process for the rest of the week, so I will return to their questions again! Finally, I say,

"Tomorrow, we will continue the design cycle and plan the next step for STEM lab on balance!"