Grade 8 · Functions · MAT-08-FN-007
Find Slope from Two Points
Represent and solve find slope from two points problems using precise mathematical notation, multiple representations, and justified reasoning.
Learning objectives
What you should be able to do
- Represent and solve find slope from two points problems using precise mathematical notation, multiple representations, and justified reasoning.
- Interpret and verify find slope from two points results in context, including units, constraints, and reasonableness.
Prerequisite check
Make sure the foundation is ready.
Grade 8 uses this prerequisite as active knowledge in a more formal representation.
Learn
Build the idea from meaning, not memorization.
Meaning and structure
Find Slope from Two Points belongs to functions. Identify the governing property or relationship before choosing a procedure.
Multiple representations
Represent find slope from two points numerically and symbolically, then connect it to the Grade 8 Math Box. Tables, graphs, equations, coordinate models, diagrams, and verbal descriptions must agree.
Verification and interpretation
Check with substitution, an inverse operation, an equivalent representation, geometric invariants, estimation, or context. State whether the result is exact or approximate and preserve relevant units and constraints.
Math Box · Interactive lesson
Touch the math. Change it. See what stays true.
Use the interactive model before and after the worked examples. Change the inputs, make a prediction, then use the model to test whether your reasoning holds.
Slope & Rate-of-Change Lab
- Model find slope from two points in the Math Box.
- Change one input and predict which quantities or invariants should change.
- Explain what the visual, equation, and numerical result say about the same relationship.
Worked examples
Twenty different ways to see the concept work.
Find slope through (0,2) and (2,4).
m = (4-2)/(2-0) = 1Subtract coordinates in the same order.
Find slope through (1,6) and (4,12).
m = (12-6)/(4-1) = 2Subtract coordinates in the same order.
Find slope through (2,12) and (6,24).
m = (24-12)/(6-2) = 3Subtract coordinates in the same order.
Find slope through (3,20) and (8,40).
m = (40-20)/(8-3) = 4Subtract coordinates in the same order.
Find slope through (0,10) and (2,20).
m = (20-10)/(2-0) = 5Subtract coordinates in the same order.
Find slope through (1,9) and (4,27).
m = (27-9)/(4-1) = 6Subtract coordinates in the same order.
Find slope through (2,7) and (6,11).
m = (11-7)/(6-2) = 1Subtract coordinates in the same order.
Find slope through (3,13) and (8,23).
m = (23-13)/(8-3) = 2Subtract coordinates in the same order.
Find slope through (0,9) and (2,15).
m = (15-9)/(2-0) = 3Subtract coordinates in the same order.
Find slope through (1,6) and (4,18).
m = (18-6)/(4-1) = 4Subtract coordinates in the same order.
Find slope through (2,14) and (6,34).
m = (34-14)/(6-2) = 5Subtract coordinates in the same order.
Find slope through (3,24) and (8,54).
m = (54-24)/(8-3) = 6Subtract coordinates in the same order.
Find slope through (0,8) and (2,10).
m = (10-8)/(2-0) = 1Subtract coordinates in the same order.
Find slope through (1,12) and (4,18).
m = (18-12)/(4-1) = 2Subtract coordinates in the same order.
Find slope through (2,9) and (6,21).
m = (21-9)/(6-2) = 3Subtract coordinates in the same order.
Find slope through (3,17) and (8,37).
m = (37-17)/(8-3) = 4Subtract coordinates in the same order.
Find slope through (0,7) and (2,17).
m = (17-7)/(2-0) = 5Subtract coordinates in the same order.
Find slope through (1,15) and (4,33).
m = (33-15)/(4-1) = 6Subtract coordinates in the same order.
Find slope through (2,4) and (6,8).
m = (8-4)/(6-2) = 1Subtract coordinates in the same order.
Find slope through (3,10) and (8,20).
m = (20-10)/(8-3) = 2Subtract coordinates in the same order.
Practice
Guided practice with hints
01Find slope through (0,6) and (2,12).
Hint: Represent the structure first, calculate carefully, then verify with a second representation or substitution.
Answer: m = (12-6)/(2-0) = 3
02Find slope through (1,12) and (4,24).
Hint: Represent the structure first, calculate carefully, then verify with a second representation or substitution.
Answer: m = (24-12)/(4-1) = 4
03Find slope through (2,20) and (6,40).
Hint: Represent the structure first, calculate carefully, then verify with a second representation or substitution.
Answer: m = (40-20)/(6-2) = 5
04Find slope through (3,21) and (8,51).
Hint: Represent the structure first, calculate carefully, then verify with a second representation or substitution.
Answer: m = (51-21)/(8-3) = 6
05Find slope through (0,5) and (2,7).
Hint: Represent the structure first, calculate carefully, then verify with a second representation or substitution.
Answer: m = (7-5)/(2-0) = 1
06Find slope through (1,9) and (4,15).
Hint: Represent the structure first, calculate carefully, then verify with a second representation or substitution.
Answer: m = (15-9)/(4-1) = 2
Practice
Independent practice
01Find slope through (2,15) and (6,27).
Answer: m = (27-15)/(6-2) = 3
02Find slope through (3,14) and (8,34).
Answer: m = (34-14)/(8-3) = 4
03Find slope through (0,4) and (2,14).
Answer: m = (14-4)/(2-0) = 5
04Find slope through (1,12) and (4,30).
Answer: m = (30-12)/(4-1) = 6
05Find slope through (2,10) and (6,14).
Answer: m = (14-10)/(6-2) = 1
06Find slope through (3,16) and (8,26).
Answer: m = (26-16)/(8-3) = 2
07Find slope through (0,3) and (2,9).
Answer: m = (9-3)/(2-0) = 3
08Find slope through (1,9) and (4,21).
Answer: m = (21-9)/(4-1) = 4
Common mistakes
Learn to catch the error, not just the answer.
Outputs may repeat; one input cannot have two different outputs.
Slope is change per unit; intercept is output at x=0.
Applications & challenge
Use the idea beyond a single exercise.
Applications
- Model constant rates and starting values with tables, graphs, and equations.
- Compare functions by rate of change and initial value.
Challenge problems
Find slope through (2,17) and (6,37).
m = (37-17)/(6-2) = 5
Find slope through (3,27) and (8,57).
m = (57-27)/(8-3) = 6
Find slope through (0,2) and (2,4).
m = (4-2)/(2-0) = 1
Find slope through (1,6) and (4,12).
m = (12-6)/(4-1) = 2
Flashcards
Retrieve it from memory.
Flashcards
Card 1 of 4
Game mode
Grade 8 Algebra & Modeling Sprint
Solve find slope from two points problems and justify each result with a valid verification method.
Practice
Mastery check
01Find slope through (2,12) and (6,24).
Answer: m = (24-12)/(6-2) = 3
02Find slope through (3,20) and (8,40).
Answer: m = (40-20)/(8-3) = 4
03Find slope through (0,10) and (2,20).
Answer: m = (20-10)/(2-0) = 5
04Find slope through (1,9) and (4,27).
Answer: m = (27-9)/(4-1) = 6
05Find slope through (2,7) and (6,11).
Answer: m = (11-7)/(6-2) = 1
06Find slope through (3,13) and (8,23).
Answer: m = (23-13)/(8-3) = 2
07Find slope through (0,9) and (2,15).
Answer: m = (15-9)/(2-0) = 3
08Find slope through (1,6) and (4,18).
Answer: m = (18-6)/(4-1) = 4
Terminology
Words to know
- function
- A relation assigning exactly one output to each input.
- slope
- Vertical change divided by horizontal change for a nonvertical line.
- y-intercept
- The output where a graph crosses the y-axis.
- rate of change
- Output change per unit input change.
Continue learning
Connected concepts
Curriculum references
Standards and instructional references
California Mathematics Framework (2023)
Grade 8 instructional guidance, mathematical practices, modeling, and progression toward high-school mathematics.Common Core State Standards for Mathematics — Grade 8
Grade-level expectations for real numbers, equations, functions, geometry, and statistics.Principles to Actions: Ensuring Mathematical Success for All
Research-informed emphasis on reasoning, representations, discourse, productive struggle, and conceptual understanding.