10th Grade · Week 1 of 36 · Math

Geometry undefined terms; segments, rays; distance

Learning goal This week's job: Geometry undefined terms; segments, rays; distance.

1. Hook

How to do this lesson online
  1. Read (or listen to) what you’re learning. Don’t jump to the quiz.
  2. Walk the worked example. Then use the interactive lab on this page.
  3. Guided set → independent set → mastery check → teach-back.
  4. If you write a paper, stay on campus: Citation Helper, Source Library, Paper Studio.

This is self-paced homeschool on Life Academy. Everything you need is on this page.

Today's puzzle

You can't define "point" using simpler words. Geometry starts with a few undefined terms. What can you build from them?

Then: lab → guided → quiz → teach it back. The lab is the lesson, not a decoration.

2. Teach

What you're learning

Use undefined terms (point, line, plane) to define segments and rays, and find distance on a number line and in the coordinate plane.

Standards alignment: CCSS.MATH.CONTENT.HSG (domain-level; works with any state’s standards)

STEM in this lesson

STEM this week is Geometry undefined terms; segments, rays; distance: units, a model, and a check another student could repeat.

Hold onto these
  • Undefined terms: point, line, plane; defined terms include segment (two endpoints) and ray (one endpoint, extends forever).
  • Distance on a number line: |b − a|.
  • Distance formula: d = √((x₂ − x₁)² + (y₂ − y₁)²).
This week’s lesson

Segment AB has endpoints A and B; ray AB starts at A and passes through B forever. Points on −3 and 5 are |5 − (−3)| = 8 apart.

Distance from (1, 2) to (4, 6): √(3² + 4²) = √25 = 5. The distance formula is the Pythagorean theorem on the coordinate grid.

Watch one worked example
  1. Find the distance from (−2, 3) to (4, −5).
  2. Δx = 6, Δy = −8.
  3. d = √(36 + 64) = √100.
  4. d = 10.
Now you try — with me

Find the distance between (−1, −1) and (5, 7), and explain the difference between ray PQ and ray QP.

The usual mistake

Subtracting coordinates in mixed order, or forgetting to square before adding.

Why this shows up in real life

GPS, maps, and game engines compute distances with this same formula.

No classroom teacher today — this page is the lesson. Follow the how-to, then the lab, then the quiz. Follow Lesson Studio, then the lab, then the quiz. Open Transcripts for credits and grades.

Open Lesson Studio (Week 1) →

Interactive lab (on this page)

Change one variable. Record what happened. This model is the lab — not an off-site sim.

Your work — type it here

Type the answer. Then tap Check my work. This is the assignment — not optional reading.

3. Guided practice

Try these with me — type the missing word, then check.

Reveal the thinking

Find the horizontal and vertical changes, square them, add, and take the square root.

4. Independent practice

Work the set. Check when finished — this is practice (mastery quiz is next).

1. Which is undefined in geometry?
2. A segment has
3. Distance from (2, 1) to (2, 9)
4. The distance formula comes from

5. Mastery check

Scored quiz — results save to your gradebook.

1. Distance from (3, 4) to (0, 0)
2. Ray QP starts at
3. Distance between −7 and −2
4. Distance from (1, 1) to (4, 5)

Show the math — don't only tap a letter

The lab is the worked example you can move. Then the quiz checks that you own Geometry undefined terms; segments, rays; distance.

Research Desk · Transcripts · Gradebook

Honest limit: We did not film a custom movie for every core lesson. The teach-back, the on-page lab, and the campus library are the curriculum. The teach-back, the on-page lab, and Lesson Studio are the lesson.

6. Reflection / teach-back

Teach-back: Explain Geometry undefined terms; segments, rays; distance in your own words. Give one example and name the usual mistake.

Teacher notes (optional) — adult coaching script for Week 1