Substitute Teacher Guide • Grade 9 • Unit 2: Understanding Digital Images

Image Terminology — Day 1 of 2

Today's focus: Pixels & Resolution

✅ Before Students Arrive

Materials needed today:
- Graph paper (to represent a "pixel grid")
- Crayons/markers (to color in a mosaic-style pixel picture)
- Printed vocabulary flashcards
- Sorting cards: 10 image examples (photo, logo, icon, screenshot, etc.) for the raster/vector sort
Most students keep their class notebook at its usual spot in the room and use it every day (see routine below) -- but it's each student's own notebook, so a few may bring theirs from home instead. Either way, everyone should have one out.
Write today's Do Now on the board before the bell rings (see below).

📓 Daily Notebook Routine (students already know this)

Keep this going every day, in your class notebook: date today's entry, jot your Do Now response, add any new vocabulary word(s) from today's Key Vocabulary section (word + a quick picture + a simple definition in your own words), and take 60 seconds to sketch something connected to today's topic. This notebook is yours to study from, reference on projects, and pull evidence from later for your portfolio.

🗣️ Opening: Do Now

Write or project this, and have students start immediately:

“What does the number "1920x1080" mean? Take a guess even if you're not sure.”

📋 Class Plan (step by step)

Step 1 — 12 min

🗣️ Say: "Today we're looking at ___." Then walk through the point(s) below at the front of the room.

📋 Mini-lesson (12 min): introduce pixel, resolution, and aspect ratio using the graph-paper analogy.
Step 2 — 23 min

🗣️ Say: "Now it's your turn -- work on your own (or with your table) on the following."

📋 Hands-on (23 min): color in a small graph-paper grid to make a simple pixel-art image, then compare a low-resolution (few squares) vs. high-resolution (many squares) version.
Step 3 — 5 min

🗣️ Say: "Let's hear from a few people before we move on."

📋 Quick share (5 min): hold up your grids and compare.

🔑 Vocabulary Introduced Today

Pixel: The smallest single square of color that makes up a digital image, like a tiny tile in a mosaic.
Resolution: How many pixels are packed into an image -- more pixels generally means more detail.
Aspect Ratio: The proportional relationship between an image's width and height, like 16:9 for widescreen video.

✅ Wrap-Up: Exit Ticket

A few minutes before the bell, say: "Time to finish your exit ticket."

“In your own words, explain the difference between a raster image and a vector image -- no technical jargon allowed!”

Collect exit tickets (or have students leave them in the usual spot) for the regular teacher to review.

⏳ If You're Short on Time

Protect the Do Now and the Exit Ticket above all else -- those are how the regular teacher tracks daily progress. If a step above is optional/homework, or is a "share out"/discussion step, shorten or skip it first.

⏳ If Students Finish Early

Have them keep working in their notebook: add extra detail to today's vocabulary sketch, review previous vocabulary, or -- if this is a portfolio update week for this class -- work on their portfolio. Early finishers should never be idle or distracting to classmates still working.

📝 For the Regular Teacher (fill in ahead of time)

Regular teacher's name / how to reach them: ______________________________
Where finished work / exit tickets go: ______________________________
Front office extension / emergency contact: ______________________________
Anything else this class needs to know today: ______________________________