Thursday, April 7, 2016

Day 133: Desmos Marbleslides Lines & Will it Hit the Hoop? (Also Linear Inequalities)

Students started with estimating a giant Hershey's bar. Some students estimated in grams and ounces. A French student estimated in kilograms. Most students estimated in pounds. Some students thought it was really heavy and possibly 20 percent of Mr Stadel's weight. So, basically a lot overestimated, and some underestimated. For the most part students were not too courageous with their too low and too highs.
In most classes I asked what the relationship between pounds and ounces was. At least 3 in each class knew there were 16 ounces in a pound so multiply the answer by 16 ounces. We also discussed how much 2.26 kilograms was in grams. I liked how some students knew it would be a power of 10, but weren't sure if there were 100 grams or 1,000 grams in a kilogram.
I like how this student mentioned how Mr Stadel was loosely gripping the candy so it couldn't be THAT heavy.
In pairs you will login to one of your google accounts. The blog post will later be posted to this persons blog. Below was my original plan, and it was a little too ambitious because they needed most of the period to get to the Challenge slides. The first slide was one of the harder slides for most students.


  1. First you will install a Chrome extension called "Snagit". (UPDATE: Screencastify is a free Google Chrome extension that publishes to YouTube or Google Drive)
  2. Try a test recording to make sure you can hear your voices. When you try to record you must click allow to use microphone.
  3. Then you will work through Desmos Marbleslides Lines at student.desmos.com with the student code I give you.
  4. Once you get to either Challenge #1 or Challenge #2 through you will start recording, start to finish, both narrating how you are trying to solve the challenge.
  5. After you've recorded it, go to your blog at Blogger. Create a new blog post. Click the movie icon to the right of the photo icon and click on My Youtube Videos and select your video.
  6. Finally, view your blog post. Copy the link to it and click send a tweet from the sidebar on my blog.
Students struggled the most with the first slide that started with y=4x+3. They realized increasing the coefficient of x did not help. Then they decreased it. When they deleted it they were left with x. When they put in 1, they realized that it was still the same. 90% of students then tried -1x and realized it completely changed the angle. Some students tried 0 and saw that it made it a flat horizontal line. They finally made the jump to trying decimals. Some got 1/2x when trying to type 1/2x and a I showed some how to press arrow right after the fraction.
It's interesting how a majority of students who solved this challenge decided to split the pathway of the marbles with an upside down V made of 2 lines. 

I like how some students mentioned the x axis when the domain restriction was modified. Some incorrectly thought it would change the slope.
Exploring with sliders and experimenting with domain restrictions.
I liked how these students didn't put the line exactly on the top left corner of each rectangle and just let the marbles fall in.
Most students realized the y intercept would change to 0. One thought it would change the growth.
Some students only mentioned it would get steeper. It was key to also mention that it would have positive or increasing slope. Notice the reference to Slope Dude Says... "it would be puff puff positive." Saying it would slant more would not be enough. I liked how 1 partnership noted it would increase and go up by more since 2 is greater than -0.14.
I'm glad students knew the slope had to change. Some did not elaborate on how they would change it.
Changing the domain.
Once again, changing the +3 to a 0, some thought that would change how steep the line was.
Slope deals with steepness and either an increasing or decreasing line.

At first glance I thought this was a vertical line but its just a line with a slope of 80!

I couldn't remember what to call the wavy brackets. They are curly brackets or curly braces. I think I'll remember because put together they look like braces on teeth.
Students mix up positive and negative association with slope. It's on the right track, though I try to stress to my students that scatterplots have association. Lines have a slope that's either positive, negative, zero, or undefined.

Some students ignored that the domain restriction would have to change also. I understand though because this was their first introduction to domain restrictions.





Then in accelerated students worked through a Linear Inequalities activity builder by Tom Keller. I had heard about it on Desmos' weekly friday 5 blog post. I noticed that some students mistakenly made their inequalities pass through the solution points, which made the boundary line not fit the parameters. Also some did greater than instead of greater than or equal to in some situations. I had students put their screens down and look at overlays and thumb nails of their peers work as well as share solutions. We talked about how the direction of the sign tells you whether it will shade above or below the line.
2 pairs wrote equations and 1 pair wrote an inequality that passed through the points, making it the wrong boundary line.
Couple equations again.

Some students did not use the correct slope and made a horizontal inequality. I see 1 partnership in the top right shaded the wrong side of the inequality, therefore the direction of the inequality needed to be switched.

Blaise Pascal's is clever because they made it a compound inequality. The boundary line was supposed to be solid so I notice 2 pairs made it dashed.
One 1 misconception here. Easy to spot.


I can see "DOTS" shaded the wrong side of the inequality.

I then had students take out paper and start Will it Hit the Hoop? Some students enjoyed trying to bring some humor to their responses, and I think they learned a lot about modeling. I was impressed that a couple applied their science knowledge at the beginning of the lesson.

I was impressed a student mentioned Newton's Laws of gravity.
Here students found the coordinates of the hoop. As you can see only 3 partnerships interpreted that that meant the hoop was 10 feet high. 3 of them also mentioned it's 20 feet away from the shooter. (not Mr. Stadel)
Students saw the coordinate was the vertex, but only a few realized that was the highest point the basketball would reach.
Any of them that play video games are obsessed with Call of Duty Black Ops.

If I were to make a worksheet to with this activity, I'd like it in a format like the way Harrison organized he and his partner Zoe's work. I like how there's the predictions with your "eyes." Then they use the parabola to analyze and revise their prediction. Finally he has his answer key below.

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