Teaching Priority Concepts in Math: Grade 8

Tricia Profic

State Updates

Module 1 and Module 2 are available on engage for grade 8 Module 1 Link

Module 2 Link

The first quarter to half of the year’s modules are “supposed” to be available at the end of the month

Annotated sample questions from April’s state assessment are posted on engage as well Sample Questions link

Tape Diagrams

• Promote perseverance in reasoning through problems.

• Develop students’ independence in asking themselves: “Can I draw something?”

“What can I label?”

“What do I see?”

“What can I learn from my drawing?”

88 children were in swimming camp. One-third of the boys and three-sevenths of the girls wore goggles. If 34 students wore goggles, how many girls wore goggles?

Opening Exercise:

88 children were in swimming camp. One-third of the boys and three-sevenths of the girls wore goggles. If 34 students wore goggles, how many girls wore goggles?

88

34

20

Boys Girls

Wore goggles

Children at swim camp

Did not wear goggles

54

34

Wore goggles

14

94 children are in a reading club. One-third of the boys and three-sevenths of the girls prefer fiction. If 36 students prefer fiction, how many girls prefer fiction?

Try to use tape diagrams to answer the following question:

94 children are in a reading club. One-third of the boys and three-sevenths of the girls prefer fiction. If 36 students prefer fiction, how many girls prefer fiction?

Let’s practice with tape diagrams

Two pears and a pineapple cost $2. Two pears and three pineapples cost $4.50. Find the cost of a pineapple.

Example 2

Henry bought 280 blue and red paper cups. He used 1/3 of the blue ones and 1/2 of the red ones at a party. If he had an equal number of blue cups and red cups left, how many cups did he use altogether?

Example 3

Sana and Amy collect bottle caps. The ratio of the number of bottle caps Sana has to the number Amy has is 2:3. The ratio became 5:6 when Sana added 8 more bottle caps to her collection. How many bottle caps does Amy have?

Example 4

The ratio of songs on Jessa’s phone to songs on Tessie’s phone is 2 to 3. Tessie deletes half of her songs and now has 60 fewer songs than Jessa. How many songs does Jessa have?

Congruence and Rigid Motions

How do you define congruence?

Why are we defining congruence in terms of rigid motions? To avoid having to directly measure objects: Can

we really measure with accuracy?

Are opposite sides of a rectangle really congruent?

Translations

How do you define a translation?

Module definition of a translation: A basic rigid motion that moves a figure along a

given vector.

Yes, vectors in 8th grade….

Activity

Draw on paper any shape you would like and a vector

Trace that shape and vector onto your transparency

Slide your transparency moving your point A to end at your point B

visual of a translation

Reflections

How do you define a reflection?

Module definition of a reflection: A basic rigid motion that moves a figure across

a line

Also, if you connect any point to its reflected image, the line of reflection bisects that segment

Activity

Draw on paper any shape you would like and a line you would like reflect your image on

Trace that shape and line of reflection onto your transparency

Flip your transparency over to see how the image was reflected on the line you chose to draw

visual of a reflection

Rotations

How do you define a rotation?

Module definition of a rotation: A basic rigid motion that moves a figure around

a point, d degrees

Activity

Draw on paper any shape and a point you would like to rotate your shape around

Trace that shape and point on your transparency

Turn your transparency counter clockwise around the point you drew, keeping your transparency matched up with your point

Visual of a Counterclockwise Rotation

Sequencing Rigid Motions

Congruence of Figures using Rigid motions

Congruence of Angles

How to prove the congruence of angles when you have parallel lines cut by a transversal using rigid motions.

Proving the angle sum of the interior angles of a triangle is 180 degrees given known facts about straight angles and the relationships between angles with parallel lines cut by a transversal.

Today’s Task

Each pair will be given a lesson from Grade 8 Module 2 to analyze

We know that some of these lessons will need modifications to reasonably teach these concepts

Please fill out the lesson plan form

If you modify any of the class problem sets or homework assignments, please add them to the lesson plan word document

After building your lessons, we will regroup and modify the mid-module and end-of-module assessments to add multiple choice questions