You're a substitute teacher. You just got called at 6 AM for a middle school math class. The lesson plans the teacher left are vague ("students can work on their assignments") or nonexistent. You have 30 students, 45 minutes, and no idea what chapter they're on. You need something that keeps them doing math, works without knowing their curriculum, and prevents the class from descending into chaos. You need it in the next 20 minutes.
This guide is your emergency kit. Every activity listed below requires minimal preparation, works for any middle school math level, and can be deployed in under 5 minutes. Bookmark this page.
Digital Options (If Devices Are Available)
Infinilearn — The 2-Minute Setup
Setup time: 2 minutes · What you need: Devices with internet · Price: Free
This is the simplest option for a sub. Go to the Infinilearn website, have students create accounts (no email required — just a username and password), and they're playing within minutes. The adaptive system handles everything: it figures out each student's level, serves appropriate problems, and adjusts difficulty automatically. You don't need to know what chapter they're on or what level they're at.
Students play an RPG where math problems power combat. Most middle schoolers engage immediately because it looks like a game, not like school. You supervise and walk the room while the software handles the math instruction.
If the regular teacher has an Infinilearn teacher account, students may already have accounts — ask the class.
Blooket — The Crowd-Pleaser
Setup time: 3-5 minutes · What you need: Devices, projector · Price: Free
Create a free Blooket account (or use a pre-made question set — search the library for the grade level). Start a game, project the code. Students join on their devices. Multiple game modes keep energy high. Students who've used Blooket before will help others get set up.
The advantage for subs: students love Blooket and will enthusiastically participate. The disadvantage: you need to choose a question set, which requires knowing the approximate grade level and topic. Ask a student what they've been studying — they'll know.
Khan Academy — The Self-Directed Option
Setup time: 1 minute · What you need: Devices with internet · Price: Free
Write on the board: "Go to khanacademy.org. Work on [grade level] math. I'll be checking." Students who have accounts can continue their courses. Students without accounts can browse topics and practice. This is the least engaging option but requires zero preparation and keeps students doing math.
No-Device Activities
Whiteboard Relay (10 Minutes to Set Up)
What you need: Whiteboards and markers (or paper), math problems
Divide class into teams of 4-5. Write a set of 10 problems on the board (or use the ones below). Teams solve them relay-style: student 1 solves problem 1, passes to student 2 for problem 2, etc. First team with all correct answers wins. If a problem is wrong, it goes back to that student.
Emergency problem sets (use for any middle school class):
- 6th grade: 3/4 + 1/3, 2.5 × 1.6, 45% of 80, 12 ÷ 0.5, ratio of 15:25 simplified, area of triangle (b=8, h=5), 2/3 of 90, 0.75 as a fraction, 18 is what % of 60, order: 0.6, 3/5, 62%
- 7th grade: -8 + 13, -3 × -7, 2x + 5 = 17 solve for x, 15% tip on $45, -12 - (-4), 3/4 ÷ 2/3, proportional: 3/7 = x/21, 25% increase on $80, -2.5 + 6.8, |−15|
- 8th grade: 3x - 7 = 2x + 5, slope of (2,3) and (6,11), √144, y = 2x + 1 find y when x = -3, simplify 3² × 3⁴, solve 2(x+3) = 18, distance: (0,0) to (3,4), 4.2 × 10³ in standard form, Is √10 rational?, volume cylinder r=3 h=5
Math Bingo (5 Minutes to Set Up)
What you need: Paper, pencils
Students draw a 5×5 grid and fill it with numbers you specify (e.g., "write any integers from -10 to 25" or "write any decimals between 0 and 5"). You call out math problems instead of numbers. Students solve the problem and mark the answer if it's on their grid. Five in a row wins.
This works for any topic and any level because students self-differentiate through which numbers they choose.
Four Corners
What you need: Paper signs A, B, C, D posted in corners
Display multiple-choice math problems (write on board or project). Students physically walk to the corner matching their answer. Reveal the correct answer. Students in wrong corners sit down (or lose a point). Last student standing wins. Gets students moving and reveals misconceptions instantly.
Math Jeopardy on the Whiteboard
What you need: Whiteboard, pre-written questions
Draw a Jeopardy grid: 5 categories, 5 point values (100-500). Categories can be generic: "Fractions," "Equations," "Geometry," "Word Problems," "Grab Bag." Write problems in advance (or use the emergency sets above at increasing difficulty). Teams choose categories and answer for points.
Survival Tips for Math Subs
- Ask the students what they're working on. Middle schoolers know their current unit. "What chapter are you guys on?" gives you the topic for the day. They'll tell you honestly because they'd rather do relevant math than random busywork.
- Have a backup plan. Technology fails. If devices aren't charged, WiFi is down, or the computer cart is missing, you need a no-tech option ready. The whiteboard relay and four corners always work.
- Don't try to teach new content. Your job as a sub is to keep students productively engaged with math, not to introduce new concepts. Review, practice, and games are appropriate. New instruction is not — it'll confuse students and frustrate the regular teacher.
- Circulate constantly. Whether students are on devices or doing a paper activity, walk the room. Your physical presence prevents off-task behavior. Glance at screens to verify students are actually on the math game, not on something else.
- End 5 minutes early for cleanup. Nothing derails a sub day faster than students leaving a mess of whiteboards, markers, and paper. Build cleanup time into your plan.
Building a Sub Day Kit
If you sub regularly for math classes, keep these ready:
- This article bookmarked on your phone
- A free Blooket account with pre-loaded question sets for grades 6, 7, and 8
- The emergency problem sets above printed or saved on your phone
- A deck of cards (for math card games if all else fails)
- The Infinilearn URL memorized: students can get started while you figure out the rest of the period
The Bottom Line
Substitute teaching a math class doesn't have to be survival mode. With Infinilearn (2-minute setup, adaptive, free) for device days and whiteboard relays or math bingo for no-device days, you can keep any middle school math class productively engaged for a full period. The key is having your options ready before you walk in the door — because once 30 middle schoolers sense that you don't have a plan, it's too late.