Substitute Teacher Guide • Grade 9 • Unit 2: Understanding Digital Images
Image Terminology — Day 2 of 2
Today's focus: Raster vs. Vector
✅ 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's the difference between a pixel and a resolution?”
📋 Class Plan (step by step)
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Step 1 — 15 min
🗣️ Say: "Now it's your turn -- work on your own (or with your table) on the following."
📋 Hands-on sort (15 min): sort 10 image examples into Raster or Vector piles, with a reason for each.
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Step 2 — 10 min
🗣️ Say: "Here's what we're doing next." Then read the instructions below to the class.
📋 Vocabulary review game (10 min): matching flashcards to definitions.
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Step 3 — 3 min
🗣️ Say: "Before the bell, everyone needs to finish the exit ticket."
📋 Exit ticket (3 min).
🔑 Vocabulary Introduced Today
- Raster Image
- An image made of a fixed grid of pixels; enlarging it too much makes it blurry.
- Vector Image
- An image built from mathematical paths that can scale to any size without losing quality.
✅ 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: ______________________________