Category Archives: Geometry

Ethan Hall, teacher and web entrepreneur from Israel, emailed me this morning asking me to check out his visual patterns generator on There’s a lot of cool graphing tools other than the VP generator. I’m kinda blown away. Go play! Go do math!

Also posted in Algebra, Course 1 (6th Grade Math), General, Math 8, Problem Solving | Tagged , , | 6 Responses

Rigid Transformations

My 8th graders are learning about rigid transformations. I want to add a bit more complexity to what our book is asking the kids to do. For example, the book is having them reflect a shape mainly across the x-axis or y-axis, or on a rare occasion, reflect it across “the horizontal line that goes through […]

Also posted in Math 8 | Tagged , , , , , , | 8 Responses

Four Square and Other Questions

One afternoon during recess I noticed that the Four Square grid at our school had been enlarged. Naturally I yelled out to the kids, “Hey kids, when did they make this larger? I wonder what percent increase this is. What do you think?” Taking a nanosecond pause from their game, they yelled out their estimates, anywhere from 50% to […]

Also posted in Course 1 (6th Grade Math) | Tagged , , , , , , | 3 Responses

Driving Them Nuts

I’m proud of my students. I’m proud of what we do in room 15. My classroom. My home away from home for the last 11 years. These bopping teenagers, sullen one minute bubbly the next, hormonal but invincible. They don’t all love math like I do. (Not everyone loves college football, but we get along.) What is happening […]

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First Two Days of School

Tomorrow is the day. I’m excited to meet my new Math 6 students — all 71 of them, two classes of 36 and 35. I should know about half of the 33 Math 8 kids because I taught half of them in 6th grade. Then I get a big break in class size with just 9 students in […]

Also posted in Course 1 (6th Grade Math), Math 8 | Tagged , , , , , , | 19 Responses

What the Kids Thought

Recently Dan Meyer asks Mathalicious which of these three questions is “real world”? Karim Ani, founder of Mathalicious, and others have opined without consensus on this particular question and on the general notion of real-world vs. fake-world problems. I wonder what my 8th grade geometry kids think of this question. I give them Version A on a strip of paper and ask them to work on […]

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Hotel Snap

[NCTM Illuminations has my blessings and thanks to re-write and feature this lesson on their site.] Andrew Stadel and I recently presented this task at the 2013 CMC‘s North and South Conferences. The Challenge As a team, build a hotel that yields the highest profit [score]. Rules and guidelines for building the hotel Each cube represents a […]

Also posted in Algebra, Course 1 (6th Grade Math), Problem Solving | Tagged , , , , , , , , , | 9 Responses

Technology and Construction Papers are Cool

Big-time struggles for my 8th graders on this problem from Five Triangles mathematics. The one student who got it also struggled, but he was good about our rule of “never tell an answer.” What I gathered from seeing their boards and listening to them explain: They wanted to find the area of the parallelogram first. So […]

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Venturing Into the Sequel of Penny Pyramid

I didn’t get around to doing Penny Pyramid when I first saw it last year. But Dan‘s 3-post series and Nathan‘s recent mention of it were the reminders I needed to make it happen. Act 1 how many pennies how much money is that how long did it take who in their right mind would do this/who has that patience how much […]

Also posted in Algebra, Problem Solving | Tagged , , , , , | 2 Responses

When I Let Them Own the Problem

From our textbook: Stuff like this makes my heart sink. (I actually wrote that it makes me fart — but that’s very unladylike. And I’m trying to write better.) There is essentially nothing left in this problem for students to explore and figure out on their own. If anything, all those labels with numbers and variables […]

Also posted in Algebra, Problem Solving | Tagged , , , , , , | 30 Responses