# Ep 168: Guessing in Math Class

September 05, 2023 Pam Harris Episode 168
Math is Figure-Out-Able with Pam Harris
Ep 168: Guessing in Math Class

Let's do some guessing! In this episode Pam and Kim develop some functional reasoning by analyzing the relationships between their guesses and reality.
Talking Points:

• Pam's guesses using her pop culture knowledge
• How would you know if you are a good guesser?
• Graphing guesses and actual age as an ordered pair
• Using the data to discuss the meaning of y=x
• The parent function for building all functions

Check out our social media
Instagram: Pam Harris_math
Facebook: Pam Harris, author, mathematics education

Pam  00:00

Hey, fellow mathematicians. Welcome to the podcast where Math is Figure-Out-Able! I'm Pam.  And you found a place where math is not about memorizing and mimicking, waiting to be told or shown what to... waiting to be told or shown what to do. But it's about making sense of problems, noticing patterns, and reasoning using mathematical relationships. We can mentor students to think and reason like mathematicians do. Not only our algorithms really not very helpful in teaching mathematics, but rotely repeating steps actually keeps students from being the mathematicians they can be. Whoa!

Kim  00:07

And I'm Kim.  Hi, Pam.

Pam  00:41

Kim, I'm sitting here with my pen in hand. I'm going to bet you have a pencil.

Kim  00:45

I do, but it has no eraser, and I'm super sad about that.

Pam  00:48

Oh.

Kim  00:48

Actually, you know...

Pam  00:49

We should probably stop recording right now if you don't have an eraser.

Kim  00:52

Well, I'll be okay because I found in my kids like art table drawers. I forgot about these. But you can buy Ticonderoga erasers and they are not shaped like you know the standard, rubber pink eraser thing. You know what I'm talking about it's kind of...

Pam  01:09

The rectangular prism one?

Kim  01:11

Yeah, yeah, yeah. This one is super cute because it's shaped exactly like a fat pencil. It's got a pink eraser and a little. I'll have to show you sometime. They're super cute. But I found those, and I forgot how much I love them.

Pam  01:12

(unclear) Is it kind of like you're holding a pencil, but you're holding an eraser?

Kim  01:26

Yes, yes.

Pam  01:27

Ah. Okay.

Kim  01:28

Yeah, it's completely shaped like a pencil.

Pam  01:30

So, you're actually smiling with your Ticonderoga eraser.

Kim  01:33

But it's nubby. It's like two inches long and really fat. So, yeah. It's not full. Anywho. Hey, we got a... We're a mess. We got the best review. I want to share it with you. Oh, cool. Okay. So, it's from KelseyAnderson68. And I love when it's like an actual real name instead of 06253.

Pam  01:54

I mean...

Kim  01:54

Anyway, she said...

Pam  01:55

68. I'm not quite sure 68 is really part of Kelsey's name, but okay.

Kim  01:59

Well, maybe it's her favorite number.

Pam  02:00

Kelsey could be a he.

Kim  02:01

So, she... Oh, I didn't think about that. Sorry, Kelsey, if you're a man. Anyway, they said, "Obsessed" as their title. And it says, "I listened to every episode. Every math teacher, and anyone who has an opportunity to shape children's lives needs to listen to this podcast."

Pam  02:20

Oh!

Kim  02:21

Thanks, Kelsey!

Pam  02:22

Kim  05:25

Yeah.

Pam  05:26

So, we're going to actually walk you through a similar experience of what I had there, and then we'll kind of do some math with it. So, Kim.

Kim  05:32

Yeah?

Pam  05:32

I asked you if you would go out and find 8 or 10...I don't know how many...8 to 10 celebrities, famous people-ish, and their ages. And then, you're going to tell me the famous person, and I'm going to guess their age. Which to be really clear, I'm bad at, so just like. I don't ever guess people's age because, well A, I'm bad at it, and B, I don't want to I don't mess with that (unclear)

Kim  05:54

Yeah, that's probably not a good situation.

Pam  05:57

Yeah, like it's important to people. And yeah. Anyway, okay. So, Kim, tell me a famous, relatively well-known person, and I will guess their age. Go.

Kim  06:06

Okay. The first person I found was Michael Phelps. Any idea who that is?

Pam  06:11

Okay. Yes, he's a swimmer.

Kim  06:13

Fantastic.

Pam  06:14

And funny, we think he looks like my brother Michael.

Kim  06:17

Oh, is he very tall?

Pam  06:18

I know.

Kim  06:19

Very tall, long arms?

Pam  06:20

My brother's tall with long arms. My brother, he might swim a little bit, but he's a mountain biker. So, physique wise, they look similar.

Kim  06:29

Yeah.

Pam  06:29

Like, they're...

Kim  06:30

Okay.

Pam  06:31

Yeah.

Kim  06:32

Alright.

Pam  06:33

Let's see.

Kim  06:33

How old do you think?

Pam  06:34

I'm trying to remember. Yeah, I'm trying to. I know how old my brother is. Does that count?

Both Pam and Kim  06:37

(laughs).

Kim  06:37

No. No.

Pam  06:39

I'm going to guess that Michael Phelps is about 40.

Kim  06:43

He's...

Pam  06:44

(unclear).

Kim  06:44

Want me to tell you?

Pam  06:45

No, not yet. Yeah, thanks. So, let's go through all the people, I'll guess their ages, and then you're going to go back and tell me.

Kim  06:53

Oh, okay.

Pam  06:54

Is that okay?

Kim  06:55

Yeah, it's perfectly fine. Alright. Next, next, next. Michael Jordan. You know who that is.

Pam  07:01

Ooh, another Michael.

Kim  07:02

Yeah.

Pam  07:02

Okay. I do know who Michael Jordan is. And ooh, but let me think. I... Oh. I think Michael Jordan is 55. I'm not actually sure on that one. Oh, he might be a little older than that. But I'll stick with 55.

Kim  07:16

Okay.

Pam  07:16

Okay. Yeah.

Kim  07:18

Richard Gere.

Pam  07:21

Ugh.

Kim  07:21

Wait, you don't like Richard Gere? Or is that a, "I have no idea."

Pam  07:25

Yeah, that was more of an umm. The only picture that comes in my mind right now is Pretty Woman.

Kim  07:30

Yes! And so many other great movies.

Pam  07:32

Which I liked, but shouldn't. So, Richard Gere. Richard Gere.

Kim  07:41

I wonder if anybody screaming ages in their cars.

Pam  07:43

Yeah probably, right? Yeah. 70? Is he 70? I don't know.

Kim  07:48

Okay.

Pam  07:49

Okay. I'm so bad at this.

Kim  07:50

Okay. Prince George.

Pam  07:54

Prince George. Prince George. Like, the prince in England? That prince?

Kim  07:59

Prince. Should I?

Pam  08:01

Not like the musician that we used to? Prince who died? Not that one? No. Not Prince, not boy George. Prince.  Ah, that's who. Yeah, I was putting those two together. Okay. Prince George. Like, literally like the son of...

Kim  08:13

The child of the Prince and Princess of Wales. Yeah.

Pam  08:17

Yes. Okay. I think he's 8.

Kim  08:19

Okay.

Pam  08:19

Okay.

Kim  08:20

Pam  08:22

I'm not sure I knew his name was George. Okay, go on.

Kim  08:27

Pam  08:32

Well, funny. Our church youth group the other night, we were doing a karaoke. And I said, "Let's do a Beatles song!" And somebody said, "Who's the Beatles?" And I was like, "What?!"

Kim  08:39

Oh, I know. They're so young.

Pam  08:41

And then somebody said, "They're all dead." And I was like, "Wait, I don't think Paul McCartney is dead." Anyway.

Kim  08:47

Yeah. (unclear).

Pam  08:48

Sorry. Paul McCartney. Is Paul McCartney 75? I'm so bad at this. That's my guess. Paul McCartney is 75.

Kim  08:56

Okay, alright.

Pam  08:56

Okay,

Kim  08:57

Pam  09:00

Ugh. Now, that sound was, "Oh, I feel like a dork" because I know that he's a rapper, but that's about all I got. And I also am really clear. I just spelled his name wrong because I literally wrote the letter M and. I think it's E-M. Is that right? (unclear).

Kim  09:13

E-M. Yeah. E-M.

Pam  09:14

Yeah. Anyway, so Eminem. Eminem is 40. I have nothing. I have no idea. Okay.

Kim  09:20

Alright. Serena Williams.

Pam  09:26

Serena Williams is totally cool and has a sister, and they play tennis.

Kim  09:29

Yeah.

Pam  09:32

36.

Kim  09:35

Okay.

Pam  09:36

I don't know, that might... She might not be that old. I don't know. Okay.

Kim  09:40

Alright. See you've done great. You've known who all these people are. What about Clint Eastwood?

Pam  09:48

He's still alive. Okay. That guy's gotta be ancient. 85. I'm thinking 85. (unclear). Yeah, I don't know.

Both Pam and Kim  09:58

85. Okay.

Kim  09:58

Alright.

Pam  09:59

Yeah. Now, my parents who are not quite 85 are going to be mad that I said that was ancient.

Both Pam and Kim  10:02

(laughs).

Kim  10:04

I actually was talking about age with a friend the other day. And she's 51. And I said 51's not old at all because I'm, you know, about to be 45. And I said to her son, "Do you think that's old?" And he was like, "Yes." Okay, kid.

Pam  10:23

Yeah, age is kind of was relative.

Kim  10:25

Mmhmm, absolutely.

Pam  10:26

How close you are things. Mmhmm.

Kim  10:27

Alright, last one.

Pam  10:27

Okay. Alright.

Kim  10:29

Kylie Jenner.

Pam  10:34

Kylie Jenner, who used to be Bruce Jenner, I believe.

Kim  10:38

No, no, no.

Pam  10:38

Do I have the right?

Kim  10:39

No, not the right person.

Pam  10:41

Oh, I don't know who that is then. Kylie Jenner.

Kim  10:43

Okay, well you're still going to have to guess.

Pam  10:44

Kylie Jenner. Okay, I'm going to have to guess. I don't know who this person is.

Kim  10:47

Okay.

Pam  10:47

So, that's going to be hard. Are they related to?  Caitlyn. (unclear).

Kim  10:50

They are. Caitlyn is who you're thinking yeah.

Pam  10:53

(unclear). Okay. Kylie Jenner.

Kim  10:58

Mmhmm.

Pam  10:58

No hints, huh. No hints?

Kim  10:59

No hints.

Pam  10:59

Okay, I'm saying 26. I have nothing. I don't know.

Kim  11:03

Okie doke.

Pam  11:04

Alright. How old is Michael Phelps really?

Kim  11:07

You said 40. He's actually 38. (unclear).

Pam  11:12

(unclear). Alright, alright. Cool. Michael Jordan. How old is he?

Kim  11:16

You said 55. He's actually 60.

Pam  11:19

Ooh, a little older. Okay. Okay. How about Richard Gere?

Kim  11:25

73.

Pam  11:26

Hey! Okay, alright.

Kim  11:28

I know, you're doing so well.

Pam  11:29

70. I said 70. 73 Alright. How about Prince George, little guy?

Kim  11:32

Little guy. You said 8. He's actually 10.

Pam  11:36

10. That's funny because I actually thought he might have been more like 6. But okay. What's last time I paid attention to? Paul McCartney I said was 75, but he's actually?

Kim  11:46

81.

Pam  11:47

81. Alright, not too bad, not too bad. Eminem, I thought was 40.

Kim  11:51

He's 50.

Pam  11:53

Oh, okay. (unclear).

Kim  11:54

I was surprised by that one. Yeah.

Pam  11:56

Alright, alright. Serena Williams I thought was 36.

Kim  12:00

She's 41

Pam  12:02

Woah!

Kim  12:03

Right?

Pam  12:03

Man, those guys hold their age well. Both sisters. That's cool. Those guys are athletes.

Kim  12:08

Oh, best. Yeah. Best tennis ever.

Pam  12:10

Yeah. Alright, Clint Eastwood.

Kim  12:14

He's 93.

Pam  12:16

Woah! So, I said 85 was ancient. What does that mean 93?

Kim  12:20

93. Yeah.

Pam  12:21

Way to go, Clint! Alright.

Kim  12:22

Yeah.

Pam  12:22

That's pretty cool. Okay, cool. And then, the person I don't know. And I can't even read my own writing. Is it Kylie Jenner? Yeah. Okay, who is that?

Kim  12:31

One of the daughters. One of the Jenner girls.

Pam  12:34

Ah, okay, okay.

Kim  12:35

I couldn't name them all. There is one named Kim. Because you know, I know that.

Pam  12:39

You know that because you're name is Kim.

Kim  12:41

Courtney. There's a Courtney. Anyway. She is 25.

Pam  12:45

Oh!

Kim  12:46

Your best guess was somebody you didn't even know. Look at you. You are a good guesser.

Both Pam and Kim  12:49

(laughs).

Pam  12:51

That's terrible. Well, so that then becomes the question. So, in this moment, Gail Burrill paused. She gave us a bunch of famous people...different famous people obviously...and asked us to guess their age. And then, she told us their correct ages. And then she said, I'll never forget, "How do you know if you're a good guesser?" And I started. I was like. Now, I'm not going to give away what was going on my head quite yet. But like, Kim, you said I was the best guesser for the one I didn't know, and you said that because I was only one off. Right? Like, her age is 26, and I said 25. Some of them I was way far off. Eminem I was 10 off. Was I any any further off?

Kim  13:31

Nope, just that one.

Pam  13:32

Eminem was my worst. I mean, I was 8  off for Clint Eastwood. So, are you a good guesser? Like, what does it mean to be a good guesser? So, a couple of things that we could do right now. Let's say that I was working with middle school kids? Could I find the differences between those guesses? Because I just kind of did. One of them, I said I was 10 off, so that would be like 10. And since I'm in middle school, could I even do... Maybe I was in fifth grade. I could just find how far off I was either direction, and we could represent it with a positive. It's that 10. You wouldn't know if I was 10 over, 10 under. You just know I was 10 years off. But if I was in middle school, could we actually represent like... I don't know. Do you want over to be bad? So, like if I was over, then it would be negative 10. I think I was under. I was under, so maybe that would be a 10. I was under 10 years that would be 10. But if I was over 10... Was I over on any of them? Did I always guess under? Oh, Michael Phelps I was over.

Kim  13:33

Mmhmm.

Pam  13:42

You were over for Kylie Jenner and Michael Phelps. Yeah. So, like Kylie Jenner I'd be negative 1. Michael Phelps I was 2 over, so it would be negative 2. And then, we could kind of maybe find the mean of those. Could we average those differences? And we can kind of get a sense for maybe who in the class was the best guesser. What would we be looking for? A high mean? A low mean? Any ideas, Kim?

Kim  14:52

Would it be be a low Mean?

Pam  14:54

Because?

Kim  14:55

Because they're the closest to age.

Pam  14:58

To the actual. Yeah. Like, if they were all close, then I would have a low mean. In fact, maybe I would even want a 0 mean, if possible. Except. It's interesting. Like, what could happen? What if I had a 0 mean? What could be true?

Kim  15:14

I mean, what if you guessed off by 20 one time and over by 20 another time.

Pam  15:20

Bam (unclear)

Kim  15:20

Like, you're a horrible guesser, but either way.

Pam  15:23

Yeah. So, there's some nice conversation that we could have about what "mean" means. What is an average? And then, we could also have conversations about integers and how a negative 20 could sort of cancel out a positive 20. And that idea of 0 pairs could come up. And so, lots of nice things. Not actually where Gail Burrill was going. So, Gail Burrill in that moment said, "What if we graphed these as ordered pairs?" What if we put the actuals on the x axis. Sorry, the guesses. The guesses because that's the first one we did. So, we'll just put those on the x axis. The guesses on the x axis and the actuals on the y axis as an ordered pair. So, for example, Michael Phelps I would go over 40 because I guessed 40, and I go up 38, and I'd make a point. So, over 40, up 38 I'd put a point there on the graph. And for Clint Eastwood, I'd go way over 85 because I'd guessed 85, and I'd go up higher. I'd go up higher 93. So, my Michael Phelps guess of 40, 38 would be further to the right. I'd be over 40, but I'd only go up 38. I wouldn't go up quite as high. But my...help me...Clint Eastwood guess, I'd go way over, 85. But I'd go even farther up 93. And so then, when she said, "What would a perfect guesser look like?" That's when I really dropped my jaw. I said, "Oh, my gosh. She's going for the line y equals x." What does that mean? What does it mean where the actuals would equal the guesses? Like, I don't think I got any spot on did I? I didn't have any.

Kim  17:03

No.

Pam  17:04

Nope.

Kim  17:04

One really close. A few actually pretty close.

Pam  17:07

Like, what's one that's close?

Kim  17:10

Kylie Jenner. 25, 26.

Pam  17:13

Alright, so for Kylie Jenner, I would have gone over 26, but only up 25. But that's almost like if she was 26 years old. And I got over. I guessed 26, then I would go up 26. If I did that for everyone. Say Michael Phelps. If I had guessed 38, and he's actually 38, I would go over the same amount I would go up. And if I did that for every age, for every x value, I went up the same amount.

Kim  17:36

Yep.

Pam  17:36

Kim, can you picture what that line would look like? Like, if you were to describe the line in space? What would it would it be? Horizontal? Would it be vertical?

Kim  17:44

It would be diagonal.

Pam  17:46

Because?

Kim  17:48

Because for every... It would be 0,0. 1,1. 2,2. 3,3. All the way up to, you know, however old you can get.

Pam  17:57

If I'd guessed 100. and the person was actually 100, then I would go over 100, up 100. And if I connected all those dots. If I guessed they were a half a year old, and they were actually a half a year old. I could fill in, and I would have that diagonal line, and that 45 degree line (unclear). And that is actually what the line y equals x looks like.  And often, Kim, when I taught algebra, the line y equals x was this anomaly. It was this weird line that didn't match the pattern. Because they were used to graphing things, at least the way I was taught, and the way I saw most of my colleagues teaching. They were used to graphing y equals mx plus b. And so, there was always some sort of slope. It wasn't usually 1. Because in this case, the slope was 1 when I go over, I go up the same amount. The rate of change is always go over and up one at a time, or it could just simplify to one at a time. So, the slope, in this case, is 1. They were used to having slopes that weren't 1. And then, plus B was the y intercept. In this case, the y intercept, like you just said. If I guessed 0, they were 0 years old, the y intercept is 0. That was weird. It was weird to have a line that had a slope of 1 and a y intercept of 0. So, that was almost one they would miss if they ever find the slope between these two points.

Kim  18:17

Yeah.  (unclear) starting point. Like, this wasn't established, and then?

Pam  19:13

It is now the way I teach.

Kim  19:15

Okay.

Pam  19:16

But no.

Kim  19:16

But that's not common in high school?

Pam  19:19

Not that I've ever seen. No.

Kim  19:20

Interesting. Okay.

Pam  19:20

Kim  21:11

Yeah. When you were talking earlier, I sketched it out. So, Clint Eastwood.

Pam  21:18

Mmhmm.

Kim  21:18

You guessed 85. No, you guessed 93. So, you go over,

Pam  21:23

I guessed 85.

Kim  21:24

Yeah, you did. You guessed 85. So, did I plot that properly, then? Yeah. I think I went over 85.

Pam  21:31

Mmhmm.

Kim  21:32

And then, because he's actually 93, then I went up the actual line 93. And that put it over the line. I put it under the under the line.

Pam  21:44

Under the line? Over the line?

Kim  21:46

Did I plot it right?

Pam  21:47

I don't know. Let's say that I guessed correctly. That my guess... Let's say he was actually 85. Where's that point? Over 85.

Kim  21:55

Oh, actually no. I put it over the line. I put the points backwards. I can't listen and do at the same time. So, it would be above the line. Clint Eastwood would be above the line.

Pam  22:04

For me. For me.

Kim  22:05

For you.

Pam  22:07

Yeah, because my guess was 85, but I went way higher than and plotted the point.

Kim  22:11

Yep.

Pam  22:12

And if I'd guessed 85 and he was actually 85, that point would be over 85, up 85. But my point is over 85, up 93. Way higher, and so it'd be above the line. But in that point above line, I was under...  Yeah. Under guessing, right? So, if I was under guessing, why was my point above the line? Shouldn't an under guess be under the line? Let's do one more just really quick. So, where was a point... Did I ever over guess?

Kim  22:42

Yes, Michael Phelps.

Pam  22:42

Yes, Michael Phelps. Michael Phelps I over guessed,. It's a good thing. So, for Michael Phelps, I would go over 40 and up not as high, up only 38, and plot a point. So, a perfect guess would have been over 40 and up 40. But I only went up 38. So, that point is under the perfect guess line, even though I over guessed. I guessed he was 40, but he's only 38. I thought he was older than he is because my brother's a little bit older than that. So, an over guess is under the line. And to be clear, on purpose. So, there might be some algebra teachers out there right now going, "Pam, just do the thing, and it will..." Yeah, I know, I know. So, hang on a second. We'll talk about that. But in this moment, I didn't want it to be too obvious when I worked with students. I wanted, when I did this task with students, for students to have to think about a point under the line, under that perfect guess line, what did it mean? And a point over the line, what did it mean? I didn't want them just go, "Duh, it's under, so therefore it's an under guess" and "Duh, it's over, therefore it's an over guess." I wanted them have to actually reason through that. And then, over the next few days, we would do more tasks like this, or extensions of it, and I would warn them. I would say, "Hey, I'm going to switch it on you one of these days." Well, what do I mean by that? Well, those algebra teachers that are smiling right now, some of you might have said, "Pam, why did you graph that your guess on the x axis and the actual on the y axis." Which I think Kim is what you did. You switched them.

Kim  22:43

Yeah, I did. Do you ever ask students what would make it...

Pam  24:09

Absolutely.

Kim  24:10

Okay.

Pam  24:10

Yes.

Kim  24:10

What would make that fit in their minds maybe?

Pam  24:12

Kim  27:08

Yeah.

Pam  27:08

But then, I was able to take it into teaching. Yeah (unclear).

Kim  27:11

So, cool.

Pam  27:13

Nice. Well, Kim, thanks for getting some ages for me, so that we can play a little bit (unclear).

Kim  27:18

I'm super excited about this. I've got, you know, kids. One moving into working with lines, so I'm have to go find some ages that he will be able to guess.

Pam  27:28

Oh, some people that he'll be able to guess, and then yeah.

Kim  27:30

Yeah. For sure.

Pam  27:31

(unclear). Tell us how it goes. Tell us if he's a good guesser. But maybe less important if he's a good guesser or not, and more importantly what does he do with like thinking about whether a good guesser or not? Yeah. Nice. Cool. Ya'll, we do a task and tasks like this in my Building Powerful Linear Functions workshop, so if that interests you, check out the "All Workshops" page at mathisfigureoutable.com/workshops, where we do tasks like this to build all higher math. Because, ya'll, everyone is telling you that higher math is rote memorizable, and we're telling you that all math is actually figure-out-able. So, thank you for tuning in and teaching more and more real math. To find out more about the Math is Figure-Out-Able movement, visit mathisfigureoutable.com. Let's keep spreading the word that Math is Figure-Out-Able!