Exit Slip: Equations and Unknown Numbers closes an unknowns lesson with three short parts. Students fill missing numbers into four equations such as 7 + ______ = 15, write an equation with a box for the unknown from Maya's sticker story (8 stickers, then 14 in all), and complete a think-aloud frame that solves 12 − 5 by asking 5 + ______ = 12.
1.OA.1
“Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.”
Maya's sticker story is an add-to problem with the change unknown, the hardest position for the unknown.
1.OA.4
“Understand subtraction as an unknown-addend problem.”
Part 3 is the standard written as a frame: subtraction solved as an unknown-addend problem.
1.OA.8
“Determine the unknown whole number in an addition or subtraction equation relating three whole numbers.”
Part 1 varies the position of the blank across all four equations.
Four large-type equations with one blank each, beginning 7 + ______ = 15 and ______ + 6 = 14.
Maya has 8 star stickers, her teacher gives her some more, and now she has 14. Students write the equation with a box for the unknown, then answer how many stickers the teacher gave her.
A fill-in frame links the operations: to solve 12 − 5, think 5 + ______ = 12, so 12 − 5 = ______.
End of the unknowns lesson
Hand it out cold, with no reminders. Part 3 tells you whether the addition-subtraction connection stuck.
Grade Part 2 on the box
The number answer matters less than whether the student wrote 8 plus a box equals 14 unprompted. That box is the standard.
Three-pile sort
Sort collected slips by Part 3: blank, wrong, right. Tomorrow's warm-up group is the middle pile.
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