This complete lesson includes
• a description of the lesson,
• a Do Now that gets students thinking about ratios,
• pictures of similar pentagons,
• pictures of similar quadrilaterals, and
• a coordinate plane for students to create dilations of a given quadrilateral.
This is a great way to introduce students to the concept of similar polygons and then have them construct similar polygons through dilations.
The description of the lesson will guide you through the type of questioning you should use with your students as you begin with the Do Now . It should begin the students thinking about proportional thinking.
The description also includes some questions the students should think about as they are working with proportions. Students should not just cross-multiply and then divide. Many times students can reason what a missing number in a proportion should be if they just think about it.
Once the Do Now if complete students will think about similar pentagons, similar hexagons, and similar quadrilaterals. In all cases, they will observe that similar polygons must have the corresponding angles congruent and the corresponding sides are proportional.
The final part of the lesson is for the students to create a dilation of a polygon by using a scale factor with the coordinates of the vertices. Students will notice that the figure created through dilation will have the corresponding angles congruent to each other and the corresponding sides in the same ratio as the scale factor.
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