Skip to the content

Top 10 mistakes new substitute teachers make on the first day (2026)

Checked October 2026For TeachersKind Ideas and practicesNo affiliate links, no paid placement. How we chose

Quick answer

The number one mistake is walking in at the bell. Every sub guide we read says to arrive early, find the plans and meet the teacher next door before students come in. This list is for a new substitute teacher getting ready for a first day. Each mistake comes from a county office, a regional service unit, ASCD, We Are Teachers or a university program, and each says what to do instead.

Top 10 mistakes new substitute teachers make on the first day (2026): comparison
#NameBest forPrice
1Arriving at the bellBest for the night before a first assignmentFree
2Coming with no backup planBest for a day when the plans are missing or shortFree
3Winging it instead of following the plansBest for keeping the class on the teacher's trackFree
4Not learning any namesBest for the first five minutes with a new classFree
5Moving students out of their seatsBest for keeping the teacher's plan for the roomFree
6Giving in to "our teacher lets us"Best for the first test of a sub's rulesFree
7Threatening the whole classBest for keeping a calm room when one student acts upFree
8Leaving the class aloneBest for a day with no aide or co-teacher in the roomFree
9Letting students go earlyBest for the last minutes before a bellFree
10Leaving no note and a messy roomBest for being asked back to the same roomFree

1. Arriving at the bell

  • Best for the night before a first assignment
  • Free

The Kern County Superintendent of Schools puts this first in its 25 tips: get there early to read the plans, find materials, check the fire and earthquake steps and meet a few teachers. A 2000 ASCD article by a working sub says to come at least 30 minutes before students to check in, get the key and learn the drill route.

Costs nothing; it is a habit, not a product.

Watch for Start times and sign-in steps differ by school, so ask the office or your agency when subs should report.

What we read: the source for this entry.

2. Coming with no backup plan

  • Best for a day when the plans are missing or short
  • Free

The Rutgers Alternate Route blog tells subs to assume the regular teacher left nothing, so they are never caught without a plan, and to carry their own activities and games. Kern County's tips say to keep a story or game ready for early finishes and a few lessons that work at many grade levels.

Costs nothing; it is a habit, not a product.

Watch for A backup is for gaps; the guides still want the teacher's own plan used first wherever there is one.

What we read: the source for this entry.

3. Winging it instead of following the plans

  • Best for keeping the class on the teacher's track
  • Free

In We Are Teachers' 55 tips for subs, a teacher reminds subs that plans are left for a reason, and others ask for a detailed note on what was and was not covered. Kern County's tips say to follow the regular teacher's lesson plans and behavior system as closely as you can.

Costs nothing; it is a habit, not a product.

Watch for If a lesson truly fails, Kern County says to move to something you can teach or review, and then say so in your note.

What we read: the source for this entry.

4. Not learning any names

  • Best for the first five minutes with a new class
  • Free

Kern County's tips say to study the seating chart and pick out a few names before class so you can build rapport right away. The Rutgers blog suggests keeping the class list close, asking students to remind you, and when you get a name wrong, saying sorry, fixing it and moving on.

Costs nothing; it is a habit, not a product.

Watch for It takes more than a day to know a class, so aim for a handful of names, not all of them.

What we read: the source for this entry.

5. Moving students out of their seats

  • Best for keeping the teacher's plan for the room
  • Free

A teacher in We Are Teachers' 55 tips asks subs not to change seats, because the seating chart was made with care. The ESU 6 substitute toolbox also says not to rearrange seats or the room, except for short-term groups the lesson needs, and to make a chart if none was left.

Costs nothing; it is a habit, not a product.

Watch for If there is no chart at all, you will need to make one quickly, which takes a few minutes at the start.

What we read: the source for this entry.

6. Giving in to "our teacher lets us"

  • Best for the first test of a sub's rules
  • Free

The ASCD article warns that students notice when a sub is unsure, and it suggests saying calmly that your way may differ a little today. The ESU 6 toolbox says not to back down when students claim they never do it that way, and not to argue: this is today's procedure. A We Are Teachers contributor adds: don't be a pushover early on.

Costs nothing; it is a habit, not a product.

Watch for Some changes really are the teacher's routine, so check the plans or ask a trusted student before you hold firm.

What we read: the source for this entry.

7. Threatening the whole class

  • Best for keeping a calm room when one student acts up
  • Free

Kern County's tips say to deal with the one student, not the whole group, when a problem comes up, to skip commands and threats, and to ask for cooperation since you are on the same team. They also suggest speaking softly and waiting until everyone listens before giving directions.

Costs nothing; it is a habit, not a product.

Watch for Some situations need an adult's help fast; Kern County says to ask for help, so learn who to call before class.

What we read: the source for this entry.

8. Leaving the class alone

  • Best for a day with no aide or co-teacher in the room
  • Free

Kern County's tips say never to leave the class unattended, and the ESU 6 toolbox repeats it twice. ESU 6 also says to let only one student out to the restroom at a time and not to let students leave without a real reason.

Costs nothing; it is a habit, not a product.

Watch for If you have to step out, the guides don't say how to arrange it, so ask the office or the teacher next door what the school does.

What we read: the source for this entry.

9. Letting students go early

  • Best for the last minutes before a bell
  • Free

Kern County's tips say not to dismiss students early and to send them out in an orderly way, one group at a time. The ESU 6 toolbox adds not to release a class early to lunch or the next period unless you are told to.

Costs nothing; it is a habit, not a product.

Watch for Dismissal steps differ for buses, car riders and walkers, so ask the office how students go home.

What we read: the source for this entry.

10. Leaving no note and a messy room

  • Best for being asked back to the same room
  • Free

Kern County's tips end with tidying the room with the students and leaving a note with how the day went, who was absent and who helped or did not. The ASCD article suggests grading what you can, doing the jobs the helpers missed, keeping the note positive, then locking up and returning the key.

Costs nothing; it is a habit, not a product.

Watch for Whether to grade papers depends on the teacher; the ASCD writer marks the number of mistakes when unsure how to grade.

What we read: the source for this entry.

Also good

  • Using your phone in class: The ESU 6 toolbox says not to use a personal phone in class unless there is an emergency.
  • Skipping the teacher next door: ASCD, ESU 6 and a We Are Teachers contributor all say to introduce yourself to the neighboring teacher.
  • Talking down the school in the lounge: A We Are Teachers contributor says never to speak badly of the school, staff or students.

How we chose

We weighed these, most important first. The order is our judgement against them, not a score or a vote, and a different teacher could reasonably order it differently.

  1. Named by more than one source. Mistakes that two or more of the guides we read warn about rank above ones only a single guide names.
  2. How early in the day it bites. Mistakes that go wrong before or in the first minutes of class rank above ones that show up at the end of the day.
  3. Easy to fix. We favored mistakes a new sub can avoid with a habit, not with years of experience.

We took no money, free products or affiliate commissions for any place on this list, and no link here carries a tracking code. Every fact was read on the maker’s own page on October 30, 2026; prices carry that date because they change. See how we choose and the ad-free promise.

Questions

How early should a substitute arrive on the first day?
The ASCD article says at least 30 minutes before students, and Kern County says early enough to read the plans and meet a few teachers. Ask your school or agency when subs should report.
What if the teacher left no lesson plans?
The Rutgers Alternate Route blog says to plan for that by bringing your own activities. Ask the office or the teacher next door what the class has been working on first.
Should a sub grade the students' work?
It depends on the teacher. The ASCD writer grades unless told not to, and Kern County suggests grading papers that are easy to check. Say in your note what you graded.

Related Top Tens

Last checked October 30, 2026. Something out of date or missing? Tell us and we will fix it; makers can send corrections, never money.