Today in class our focus was dilation as a non-rigid transformation that maintains shape (corresponding angles are congruent), but not size (reduced or enlarged).
We did some activities with the coordinate plane grid and algebraic rules.
The major part of our time was devoted to learning to use Geogebra software on Chromebooks. In some classes, we constructed triangles, segments, and points of concurrency as a review and the learn what the software can do and how to experiment with it.
In all classes, we constructed a triangle, a center of dilation point, and used a scale factor of 2 to dilate the triangle. We learned some properties of dilation using tools in the software to make observations about the dilated figures. We also constructed two different sized circles and demonstrated that a translation and a dilation will map one on top of the other.
The idea of dilation defining similarity in geometric figures was shared.
On graph paper, we did EX B on p 371 and used this to glue into Geometric Truth as the example for the definition of dilation (copy from the bottom of p 371 into GT). Feel free to mark it with our observations like parallel sides, equal angles, etc. We also wrote up the conjecture on p 372 with a sketch like what we did on the computer: All circles are dilations of each other (are similar).
Finish for HW #13 if you have not already: pp 372-3: 1,3.
Students saw test scores also!
Below is a link to print a pdf of graph paper if you need it.
Final review information will go out starting in 4th period tomorrow, and will be attached on the next post.
We did some activities with the coordinate plane grid and algebraic rules.
The major part of our time was devoted to learning to use Geogebra software on Chromebooks. In some classes, we constructed triangles, segments, and points of concurrency as a review and the learn what the software can do and how to experiment with it.
In all classes, we constructed a triangle, a center of dilation point, and used a scale factor of 2 to dilate the triangle. We learned some properties of dilation using tools in the software to make observations about the dilated figures. We also constructed two different sized circles and demonstrated that a translation and a dilation will map one on top of the other.
The idea of dilation defining similarity in geometric figures was shared.
On graph paper, we did EX B on p 371 and used this to glue into Geometric Truth as the example for the definition of dilation (copy from the bottom of p 371 into GT). Feel free to mark it with our observations like parallel sides, equal angles, etc. We also wrote up the conjecture on p 372 with a sketch like what we did on the computer: All circles are dilations of each other (are similar).
Finish for HW #13 if you have not already: pp 372-3: 1,3.
Students saw test scores also!
Below is a link to print a pdf of graph paper if you need it.
Final review information will go out starting in 4th period tomorrow, and will be attached on the next post.