Vet's Diagnosis Window — Word-Problem Modeling
A shy little animal shuffles into the woodland vet clinic, and its symptom is a number STORY. Watch the x-ray act out what happened, then model it: place each amount in its spot, mark the mystery part, and dial the answer to clear the x-ray and heal your patient. A warm Grade 1 game about adding and subtracting within 20 to solve word problems with unknowns in every position, aligned to Common Core 1.OA.A.1.
A shy little animal shuffles into the woodland vet clinic, and its symptom is a number STORY. Watch the x-ray act out what happened, then model it: place each amount in its spot, mark the mystery part, and dial the answer to clear the x-ray and heal your patient. A warm Grade 1 game about adding and subtracting within 20 to solve word problems with unknowns in every position, aligned to Common Core 1.OA.A.1.
About this activity
A shy little animal shuffles into the woodland vet clinic with a symptom that is really a number story — "9 buns on a plate, 3 were eaten, how many now?" The child models the story: drag each amount into its spot, mark the mystery part, and dial in the answer. This free, interactive Grade 1 math activity solves word problems within 20 in the browser with no sign-up.
The big idea is that the unknown moves around. Across the rounds the missing number can be the result, the change, the start, a missing part, or the difference in a comparison ("12 cats and 5 dogs — how many more cats?"). Every story also offers a decoy number that does NOT belong, so the child has to map the words to the right slots before solving — the modeling is the real work, not just the arithmetic, and all the numbers stay within 20.
It is aligned to Common Core 1.OA.A.1 — using addition and subtraction within 20 to solve word problems with the unknown in all positions. No timer, no score — just calm, playful practice.
What's inside this activity
- Designed for Grade 1 learners (ages about 6–7)
- Common Core strand: Operations & Algebraic Thinking
- Aligned to Common Core standard 1.OA.A.1
How to play
Read the story and watch the x-ray act out what happened.
Drag each amount to its slot, mark the mystery part, and dial the answer.
The x-ray clears and your patient is healed; try again any time, with no timer and no score.
What your child practices
- Read a word problem and place each known amount in the right spot
- Find the unknown whether it is the result, the change, the start, a part, or a difference
- Ignore a decoy number that does not belong in the story
- Add and subtract within 20 to solve the problem
Learning goals
Solve add-and-subtract word problems within 20 with unknowns in every position — the focus of Common Core 1.OA.A.1
Model a problem before solving it, matching the words to the amounts
Handle compare problems, like how many more or how many fewer
Frequently asked questions
- What does the Vet's Diagnosis Window — Word-Problem Modeling activity teach?
- Vet's Diagnosis Window — Word-Problem Modeling is a free interactive activity for Grade 1, focused on Operations & Algebraic Thinking. Children play it right in the browser — no printing, login, or setup required.
- Is Vet's Diagnosis Window — Word-Problem Modeling free to use?
- Yes. Vet's Diagnosis Window — Word-Problem Modeling is completely free, with no signup and no paywall, on any tablet, laptop, or classroom whiteboard.
- Which ages is this activity for?
- It is designed for Grade 1 (Operations & Algebraic Thinking) and works well for whole-class, small-group, or independent practice.