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Welcome to my math blog! The purpose of this blog is to help you stay informed about our learning and experiences that have taken place during our math class. I have also included links your child (and you) may want to use in order to supplement math learning in 5th grade.

Wednesday, March 19, 2014

3-D Figures and Their Nets

A "net" is a pattern you can cut and fold to make a  model of a solid shape.  Easy enough, except 5th graders need to be able to name the 3-d shape that the net is depicting.  So, it was time to get out some nets, scissors, tape, and our journal!

The learning goal today was to identify 3-d figures by using their critical attributes.  We began by defining 3-d figures.  The kids explained that 3-d figures are solids.  They also explained they have volume so there is a length, width, and height to the shape.  When asked how we would describe a 3-d figure, I was told that we use the faces, edges, and vertices.  I asked if they could name the types of 3-d figures and after a little prodding, they came up with Prisms, Pyramids, and Curved Shape Figures.

Now the fun could begin.  I gave the students a set of nets and a set of 3-d figure illustrations.  We began with prisms.  I explained that we can determine whether a net is depicting a prism by looking for two defining features:

  1. The net should have 2 congruent polygon bases.
  2. The remaining faces should all be rectangles.
So, we looked through our nets for figures that were mostly rectangles.  We found nets for a rectangular prism, cube, triangular prism, octagonal prism, and pentagonal prism.

We found that we could determine the name of the prism by using the bases that were not rectangles.  For example, the net that had rectangular faces and two pentagons was a pentagonal prism.

As we found a prism net, we took the time to cut it out and fold it.  Then we found the matching illustration.  Using these two models, we named the number of faces (2 bases + rectangular faces), edges, and vertices.  We began to find that there was a pattern with the number of edges and a second pattern when finding vertices.

We taped each of the nets with their notes into the journal for safekeeping.

We did not finish working with nets today....we still have to do pyramids and curved surface figures.  The kids really enjoyed the lesson and I find that the more tactile the activity, the more likely it will remain in the brain.

HOMEWORK:  Countdown 5.7

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