Teaching Balanced and Unbalanced Forces

In my last post, I suggested a different way to structure your science time. It looked like this:

Use of Science Teaching Time

But as I often do, I got a little wordy! Here is the second half of that post with an example of what it would look like in the classroom.

Some FAQ’s

What do you mean “Hands on Science?”

This might be a STEM Engineering project, conducting an investigation, using science tools, making a model, exploring, experimenting. There are a lot of activities that can fit in here, but this is how you can make time for STEM.

Only 5 minutes in the textbook?

Pick out the most important section that directly relates to the task at hand. You don’t have to read the entire chapter, and you don’t have to answer the questions! There may be some days that you spend more time with the textbook, and there may be days you spend less. This isn’t meant to be set in stone, but a guideline to get you thinking about how you structure your science time.

What if I have a shorter science block?
Many teachers have mentioned to me that they are only allotted 20-30 minutes for science. You could spend Monday reviewing the textbook materials and previewing with a video clip or other activity. Then spend Tuesday doing the hands on experiment. Wednesday discuss and make connections about the hands on experiment and then go into the textbook to introduce the next topic. It is tough, but if you have such a short amount of time, you will really have to pick and choose the most important topics and activities to focus on.

What does this look like in the classroom?

balanced and unbalanced forces

Let’s say you are teaching third grade and working on:

NGSS Forces and Interactions Standard:3-PS2-1. Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object.

1. Explain that we are going to be learning about balanced and unbalanced forces. You may even have these words on sentence strips to refer to. (2 minutes)

2. Show a short clip about Tug of War. Here is short one from Youtube, a school’s field day event. Kids vs. Teachers Tug of War.  Talk with students…what happens when the forces are balanced? (There is a stand still). What happens if the forces are unbalanced? (One team wins.) What causes the forces to be unbalanced? (One side pull stronger, one side gets more people, someone lets go, etc…) Explain that not just in tug of war, but many other instances, unbalanced forces cause a change in motion. (3 minutes)

3. Read the specific section in your textbook about balanced and unbalanced forces. (You don’t have to read the whole chapter, you don’t have to answer all the questions, just pick out the important part that applies to today’s lesson.) (5 minutes)

4. Have students investigate the effect of balanced and unbalanced forces on the motion of a ball. Grab the investigation for FREE here! (30 minutes)

Screen Shot 2015-06-20 at 1.46.53 PM

Balanced and Unbalanced Forces Investigation

5. Wrap up and summarize the lesson: When the ball is still, forces are balanced. When forces are unbalanced, the ball moves. (5 min).

Happy STEM Summer Everyone!

Sarah

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One comment

  • Jon Gaffney

    I appreciate this activity, and a student of mine used it as a lesson plan. It has some solid ideas. I wanted to clarify something that is very important to get straight: unbalanced forces cause objects to *change* their motion (that is, begin to move, speed up. slow down, stop, change direction). In your key, you talk about how the bowling ball when rolling has an unbalanced force due to the push. That’s not quite true. Here’s the better way to say that: “during the push, the bowling ball has an unbalanced force on it, so it speeds up (from stopped to moving). Then, while it rolls down the lane, the forces are balanced (there is no force from the push, and there is no friction), so the ball keeps moving without any change. Then, it hits pins and slows down because there is an unbalanced force from the hit.”

    In fact, when it’s rolling there is some friction (or else it would slide), and that friction may cause a slight decrease in speed (slightly unbalanced force), but for elementary students that complexity is probably not necessary to bring up.

    Keep doing good work, and please update your key! Thanks!

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