IM 8.2.5 Lesson: More Dilations

Author:
GeoGebra Classroom Activities, IM 6 – 8 Math, IM 6 - 8 Math

Explore the applet and observe the dilation of triangle . The dilation always uses center , but you can change the scale factor. What connections can you make between the scale factor and the dilated triangle?

Your teacher will give you either a problem card or a data card. Do not show or read your card to your partner.

If your teacher gives you the problem card:If your teacher gives you the data card:
  1. Silently read your card and think about what information you need to be able to answer the question.
  2. Ask your partner for the specific information that you need.
  3. Explain how you are using the information to solve the problem. Continue to ask questions until you have enough information to solve the problem.
  4. Share the problem card and solve the problem independently.
  5. Read the data card and discuss your reasoning.

  1. Silently read your card.
  2. Ask your partner “What specific information do you need?” and wait for them to ask for information. If your partner asks for information that is not on the card, do not do the calculations for them. Tell them you don’t have that information.
  3. Before sharing the information, ask “Why do you need that information?” Listen to your partner’s reasoning and ask clarifying questions.
  4. Read the problem card and solve the problem independently.
  5. Share the data card and discuss your reasoning.

Pause here so your teacher can review your work. Ask your teacher for a new set of cards and repeat the activity, trading roles with your partner.

Triangle EFG was created by dilating triangle ABC using a scale factor of 2 and center D. Triangle HIJ was created by dilating triangle ABC using a scale factor of 1/2 and center D.

What would the image of triangle ABC look like under a dilation with scale factor 0?

What would the image of the triangle look like under dilation with a scale factor of -1? If possible, draw it and label the vertices A', B' and C'. If it’s not possible, explain why not.

If it’s not possible, explain why not.

If possible, describe what happens to a shape if it is dilated with a negative scale factor. If dilating with a negative scale factor is not possible, explain why not.

New Resources

Discover Resources

Discover Topics