##
* *Reflection:
What Goes Up, Day 1 of 3 - Section 4: Checking In

Generally, this first day was a useful formative assessment. I have a pretty good idea of my students understanding of quadratic functions now; I only wish it were deeper!

I took a quick poll of the class to find out how comfortable they were with quadratic equations. On a scale of 1 – 5, with 5 being “perfectly comfortable”, I found most students gave themselves a 3 or a 4. From their performance on the Weekly Workout and on this problem, I would have given them a 1 or a 2. So I took about 15 minutes to deliver a straightforward lecture on the three main forms of a quadratic equation, the graph of a quadratic equation, and how to solve a quadratic equation. I hope that it was time well spent. (see the whiteboard)

As this transition to the Common Core continues, I expect that I'll have to do this sort of thing from time to time. Ordinarily, I try to give my students the chance to come to a deep, conceptual understanding of things before giving them formulas or straightforward how-to's, but this is different. Here we're dealing with things the students have studied before but have either failed to remember or failed to synthesize. A lecture that lays out the how and the why in a format that's useful for taking notes seems more appropriate.

# What Goes Up, Day 1 of 3

Lesson 7 of 15

## Objective: SWBAT model projectile motion using polynomial functions. SWBAT answer questions about velocity and acceleration using quadratic function models.

## Big Idea: Projectile motion provides context for average rates of change in the context of velocity and acceleration. What goes up...

*45 minutes*

#### Individual Time

*10 min*

Hand out What Goes Up and ask students to begin working individually for about 10 minutes.

In that time, they are expected to do three things:

1. Understand the situation.

[Some students may need help understanding that the equation does not model the actual *path* of the stone, but the relationship between its *height* and *time*. The dynamic GeoGebra application may help with this.]

2. Complete the table and graph.

[Encourage students to use *at least* 1/2-second intervals for their table.]

3. Find maximum height & flight time.

[This is a good test of how well students have retained their skills from Algebra 1. The problem is open to interpretation: does the stone hit the "ground" at *h *= 5 or at *h* = 0? Depending on the class, it might be worth coming to a consensus before moving ahead.]

Please see my **Strategy Video on Individual Time** for more details.

*expand content*

#### Group Time

*5 min*

Now, announce to the class that they may begin working with their groups (pre-assigned, three or four students max.) for five minutes.

Tell that class that you expect them to:

1. Compare & comfirm their answers to parts 1 and 2

[If all goes well, this should take very little time, but this is the main purpose of the group time.]

3. Begin describing *velocity* in qualitative terms (increasing/decreasing, upward/downward, etc.)

[I expect students to be a bit confused by this question, but I want them to begin thinking about it and discussing it in preparation for the class discussion that's coming next.]

For more details, please see my **Strategy Video on Group Time**.

*expand content*

#### Checking In

*10 min*

In a 10-minute class discussion, I hope to briefly summarize and clarify the students' solutions to parts 1 and 2 of the problem, and then get them ready to investigate the average velocity of the projectile.

I plan to ask four questions to make this happen:

1. Are we all looking at the same graph?

[I will use the **GeoGebra **resource here to make the model more intuitive. If there is confusion about the actual path of the stone, this resource can help.]

2. What features are important?

[We will point out the mathematical features: symmetry, vertex, domain, intercepts. Then we will interpret these in the context of the situation. (**MP 2**)]

3. What is *velocity*?

[Students should be familiar enough with this concept, but I want to emphasize the concept of **rate of change** and also describe it qualitatively as "how quickly an object is moving in a particular direction". Of course, we will also distinguish speed from velocity.]

4. How do you calculate it?

[It is good to remind students of the general velocity formula, as well as to discuss the unit of measure for velocity. What I do NOT want to do here is to tell students how they are to compute the average velocity in this situation. (**MP 1**)]

Once we've reached the point of recalling *generally* how to calculate average velocity, I'll drop the conversation and announce: *Good. Back to work!*

*expand content*

#### Group Time

*15 min*

My expectations during this final 15-minute collaborative work time are:

1. Qualitatively describe the change in the velocity over time. As you circulate, encourage students to be attentive to precision in their writing. Saying something clearly is not an easy thing to do! (**MP 6**)

2. Estimate actual velocity at three specific times.

(For this, I expect students to use several small time intervals and consider the average rate of change of the height over that interval. They have some freedom here, but they might be encouraged to ask how the interval they choose affects the estimate. The best estimates in this case come from small intervals that are centered on the time in question, but it isn't necessary for all groups to do this. In fact, it makes for a more interesting class if different groups come up with different intervals for different (but good) reasons!)

If students get as far as considering acceleration, that's great! Encourage them to find a way to compute *average acceleration *by first finding *average velocities* on a series of equal time intervals (1/2-seconds, for instance). See the solutions resource for an example of what this might look like.

Tomorrow, we will discuss the conclusions they've drawn about the velocity of the stone, and then we'll work to answer the remaining questions.

*expand content*

*Responding to Stacy Wetcher*

Stacy,

Thanks for the feedback, and thanks for sharing this lesson on your site. I've thought quite a bit about the suggestion to add units of measurement to the resource, but I really don't think it's necessary. The opening paragraph establishes some basic units, and the rest can be derived from these. My concern is that I would not want to risk taking the focus off of the mathematical concepts by emphasizing the more "physical" elements of the scenario. In the course of the class discussions, I would check in with the students to make sure that everyone understands the units involved, but I wouldn't emphasize it. I also would steer clear of any discussion of precision (in the sense of significant digits, measurement, etc.).

Although this lesson takes a scenario from physics as a starting point, it's really a lesson about the role of the constants in a quadratic equation. Just as the students should already know how the constants *a* and *b *affect the behavior of the function *f(x) = ax + b*, I want them to begin to see how *a*, *b*, and *c* affect the function *f(x) = ax^2 + bx + c*. The physical scenario simply provides a backdrop in which these constants have some "meaning". Of course, every teacher will approach things differently, but these are my thoughts.

Thanks again for the feedback!

| one year ago | Reply

Hello!

We promote your lesson on our site (http://achievethecore.org/page/915/what-goes-up-days-1-3) and we received feedback from a user that we wanted to pass along. The user's feedback suggests that adding units of measurement to the resource would allow for more precision and context. The user was unsure where the activity was taking place (we assumed earth within our annotation), therefore leaving the context of acceleration due to gravity unknown.

Thank you for your consideration!

| one year ago | Reply##### Similar Lessons

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- UNIT 1: Modeling with Algebra
- UNIT 2: The Complex Number System
- UNIT 3: Cubic Functions
- UNIT 4: Higher-Degree Polynomials
- UNIT 5: Quarter 1 Review & Exam
- UNIT 6: Exponents & Logarithms
- UNIT 7: Rational Functions
- UNIT 8: Radical Functions - It's a sideways Parabola!
- UNIT 9: Trigonometric Functions
- UNIT 10: End of the Year

- LESSON 1: What is Algebra?
- LESSON 2: The Music Shop Model, Day 1 of 2
- LESSON 3: The Music Shop Model, Day 2 of 2
- LESSON 4: Letters & Postcards, Day 1 of 2
- LESSON 5: Letters & Postcards, Day 2 of 2
- LESSON 6: Choose Your Own Adventure
- LESSON 7: What Goes Up, Day 1 of 3
- LESSON 8: What Goes Up, Day 2 of 3
- LESSON 9: What Goes Up, Day 3 of 3
- LESSON 10: The Constant Area Model, Day 1 of 3
- LESSON 11: The Constant Area Model, Day 2 of 3
- LESSON 12: The Constant Area Model, Day 3 of 3
- LESSON 13: Practice & Review, Day 1 of 2
- LESSON 14: Practice & Review, Day 2 of 2
- LESSON 15: Unit Test