Slicing Three-Dimensional Figures- CC 7.G.3

CCSS 7.G.3 Describe the two-dimensional figures that result from slicing three-dimensional figures, as in plane section of right rectangular prisms and right rectangular pyramids.

I was really pleased with how the Carnegie Curriculum addressed this standard in the collaborative classroom text.  They devoted three lessons  to this standard:  slicing through a cube, slicing through right rectangular prisms, slicing through right rectangular pyramids.  My accelerated students really enjoyed these lessons and did a fabulous job working in their collaborative groups.

The lessons involved students making 3-d figures out of clay (although I used play doh).  Play doh worked very well and was easy to clean up and keep track of (each group got a different color play doh so there was no confusion).  I used the itty bitty containers that people give out for TOT sometimes.  This worked perfectly.  Each group had a container of play doh, a plastic knife, and dental floss.  Most groups preferred to use the plastic knife for slicing, but I did have a couple groups use the dental floss.  Students had to take turns shaping and slicing the figures.

This hand on lesson is something any teacher could easily put together.  I think it is helpful for students to see what those cross-sections look like because it can be difficult for students to sketch them.

My youngest son was not happy to see this play doh heading to school with me

Everything fit in a gallon ziplock

 Day 1 I forgot my camera so I have no photos.  Boo!  But really you can get the idea from the photos I took Days 2 and 3.  The students really enjoyed this hands on lesson and no matter how old they are, they still love play doh!

Slicing Day 2

More slicing Day 2

More slicing Day 2

 I only took one took two photos of them working the third day because I was so busy going around to each group and checking their answers with them.  Nice pyramid don't you think?

Day 3

Each lesson had a graphic organizer at the end where students had to cut out and match up the name of the cross-sectional shape with the appropriate diagram and verbal description of the way the figure was sliced.  I only took a photo of the graphic organizer the last day.  This one was done fairly neatly.  I tell you some of them lose those cutting skills they work so hard to develop in the primary grades by the time they hit 7th grade.  :)

Day 3 Graphic Organizer

I will admit that last year when I saw CCSS 7.G.3 I was kind of dreading it and thought it would be a pain and mess.  I am happy to say that the lessons were well developed and a perfect lead in to the lessons on surface area and volume (CCSS7.G.6)