Build and Describe

Two weeks ago in class we did an activity we called “build and describe.”  This is how it worked: First all students got an identical set of blocks (initially two or three, depending on age group).  Next, one student built a hidden structure and began describing it to everyone else.  The other students attempted to build the hidden structure based on the descriptions.  Once most of the students had the correct construction, the hidden one was revealed.

This is what it looked like:

The construction hidden behind a cardboard box.


Next came my favorite part, the builder’s description: The blue one is standing vertically and so is the black one.  They are not touching.  They are looking at each other.  The green one is lying on top.  There is a lot of space between the blue and the black one.

Kids successfully reproducing the structure.


Original revealed.


I was amazed at how well the kids did with the descriptions.  We tried to encourage them to use mathematical terms such as vertical, horizontal, parallel, perpendicular, etc. However, sometimes, descriptions such as “it looks like a bird” were used very successfully.  If a kid thought that he/she was done and no one had the correct construction, we would point out someone who was close and ask the creator to say something to help them fix their structure.

Here are some more constructions with their descriptions.  First, a few from our youngest group (4.5-5.5 yo).  I love how short and to the point their descriptions were.


Like a 7, green one on top.


Like the letter T.  Black one standing up, green one on top.


Looks like a rifle.  The narrow part is looking at you.  Both are lying down, the green one is closer.

Next, from our middle groups (6-7 yo).


The black one is lying down, the narrow part looking at you.  The blue one is on top of the black and the green one on top of that.  And it all looks like a snowflake.


The black one is standing up and leaning and the blue one also.


Place the black one lying down, the narrow side looking at you.  Then put the blue one on the left, also lying down.  And put the green one on the right.


Um..They’re standing up.  The blue one is on the right; they’re touching a little.  They’re forming a corner, kind of.  The blue one is facing me and the red one is facing you.


The black one is lying down.  The blue one is on top, going up.  The green one is on the blue, parallel to the black one, on the other end.  The blue one is in the middle of the black.

This one took a long time for the class to get, and you can see why.  But they didn’t give up, and eventually there was success.  Here is a picture from when they were almost there.


And finally, our oldest group (8-9 yo).  There were only two of them so they got to have many turns each.  At the end, they were building structures out of 5 blocks.  To make it a bit more fun, I was building their structures as well.  There were two times in a row when I built the incorrect structure and the other kid built the right one – I guess sometimes kids have their own language.

Here is a description that I thought was great, but unfortunately I don’t have a picture to go with it.  Perhaps you can imagine it based on the description :-).

So mine sort of looks…I’m going to say like…like the end of a rocket.  The green is laying flat and sticking out half way.  The blue is on the left, standing on it’s edge and the red is the same but on the right.  The green sticks out towards you and the blue and red are facing you.

And a few final pictures, of the most complicated structures, that I didn’t get to write down the descriptions for since I was participating in the guess building.  I believe the first one was described like an airplane and the second one like a caterpillar.  I don’t recall the last time there was such excitement on their faces.  In fact, they asked me whether we can do this activity every time at the end of class.



A few final thoughts.  This is a great activity for all ages, even adults!  It teaches one about mathematical precision and the importance of being precise with words (when I was doing my first description I found it quite difficult not to use my hands).  It is also a great way to introduce some terminology, such as parallel, perpendicular, edge, face, angle, etc.  In addition, it has an element of “secrecy,” something we found to be a big hit with every age group.  And finally, it is just a ton of fun!

About aofradkin

I enjoy thinking about presenting mathematical concepts to young children in exciting and engaging ways.
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7 Responses to Build and Describe

  1. bovetsky says:

    Yes, description of anything in simple words is the hardest part for the kids of any age. I found it working with AP calc and physics classes 🙂 Especially this year with new AP physics course that concentrates mostly on concepts.


    • aofradkin says:

      How much do you think does the ability to describe things well correlate with age?


      • bovetsky says:

        If you do not teach your students to do it, it will “never” develop. It is a result of a hard work on both student and teacher parts. Obviously, it depends of age. I would say it goes hand in hand with a general language/reading skills development.


  2. bovetsky says:

    Sorry, in a previous comment I meant “it depends on age”. I do not know how to edit comments 😦


  3. Simon Gregg says:

    Great activity and great descriptions, and I agree with your final thoughts. And yes, because it’s a barrier game it’s a lot more fun. I recently did this kind of thing with interlocking cubes.


    • aofradkin says:

      It seems like this is the sort of activity that you can (and should) do every so often with different mediums. We have plenty of interlocking cubes, so perhaps we’ll give that one a shot at some point!


  4. David says:

    Other pluses: kids like building things, telling stories, and playing games. 🙂


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