Tag Archives: geometry

Discovering the area of a trapezoid

Posted on December 29, 2017 by aofradkin

Below is a guest post by Dmitry Bryazgin (originally written in Russian). Dmitry runs a small math circle near Princeton for students in grades 3-5. On the particular day described in the post, there were 4 students present. The main … Continue reading →

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Isometric graph paper and 3D pictures

Posted on December 8, 2017 by aofradkin

Translated from this post by Jane Kats. At our math festivals and during Mousematics lessons we actively use isometric graph paper, aka “triangular grid paper”.  Sheets with a triangular grid can be downloaded on our site here in the free downloads … Continue reading →

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Fun with pentacubes

Posted on December 4, 2017 by aofradkin

Today we started a unit on geometry with the second graders.  The first activity had them explore how many different structures can be made out of 4 snap cubes.  They very quickly came up with the five tetrominoes: After a … Continue reading →

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A math-inspired love story in verse

Posted on October 21, 2017 by aofradkin

For post #100 on this blog I wrote a poem.  This is post #200 and I decided to start a tradition. This is a poem written jointly with Allison Bishop.  It is an epic love story.  Math is involved.  The … Continue reading →

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A figure with pointy things and a line, a line, and a line

Posted on October 13, 2017 by aofradkin

Look at the title.  Did you guess that this was a description of an acute triangle? This description was from a student in my third grade class.  Let me assure you, this student knows how to recognize an acute triangle … Continue reading →

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As many opinions as there are shapes: fun with “Which one doesn’t belong – A shapes book”

Posted on October 7, 2016 by aofradkin

Last week, the main theme of both my Kindergarten and my second grade math classes was geometry.  We did a number of activities that explored various shapes and their properties, but the biggest hit in both classes was Which one … Continue reading →

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Exploring Rectangles

Posted on September 17, 2016 by aofradkin

Friday is a special day in our math classes at the Main Line Classical Academy.  We read and discuss mathematical stories and we do exploration projects.  Here is the project that we did with the 2nd-4th grades last Friday. It … Continue reading →

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What makes a triangle?

Posted on July 10, 2016 by aofradkin

Last weekend we went to a wonderful family camp with an Ancient Greece theme. I was tasked with coming up with a fun, hands-on geometry lesson for 5-7 year olds. These were my criteria for the activity: 1) Easy prep … Continue reading →

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Diagonal is not straight

Posted on May 25, 2016 by aofradkin

Zoe and I often play games where one of us makes a figure with some objects (stones, chips, snap-cubes, etc.) and the other one has to make an identical figure.  Today, for this purpose, we were using an old Russian … Continue reading →

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Making Cubes

Posted on May 7, 2015 by aofradkin

Today I used Magformers to show Zoe how to make a cube. Then I said, “Now you do it.” She made me three! Here are the step-by-step pictures for one of them (if you go through them very quickly, it’ll … Continue reading →

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