An Area and Perimeter Unit for Grade 3, From Unit Squares to Gardens
An Area and Perimeter Unit for Grade 3, From Unit Squares to Gardens
Third grade teachers who need an area and perimeter unit can use Area & Perimeter, which moves from counting unit squares to formulas, compound shapes and garden problems, with an answer key and no prep. It comes on its own or as part of the Elementary Math Units Bundle, where it joins place value, fractions and an assessment toolkit for $69.99 instead of $99.96.
See the area unit →Area & Perimeter is a no-prep printable unit with an answer key that teaches third graders area and perimeter through unit squares, then formulas, compound shapes and garden problems. It is part of the Elementary Math Units Bundle ($69.99; the four units cost $99.96 separately), which also contains Numbers to 1000, Fractions with visual models and a Math Test Prep & Assessment Toolkit. The bundle is written for Grades 3–5 and is not a complete year of math.
The resources
Elementary Math Units Bundle, Grades 3–5
Start with the first resource; the others are optional add-ons. Open any cover for the full contents and price.
Elementary Math Units Bundle | Numbers to 1000, Fractions, Area & Perimeter, Test Prep | 4 Units | Grades 3–5
Algebra Foundations Bundle | Expressions, Equations, Real Numbers & Ratio | 4 Workbooks | Grades 5–9
Pre-Calculus Prep Bundle | Quadratics, Function Transformations, Derivatives & Graph Analysis | 3 Workbooks | Grades 9–12
Teach-Life-Balance: The Complete Time-Saving Course for Teachers (incl. Planner, Guides & Templates)
The real problem
Why third graders mix up area and perimeter
Area and perimeter look simple on paper and confuse third graders for years. Both involve a rectangle, both involve counting, and both produce a number, so children swap them freely. Ask for the area of a 4 by 3 rectangle and you will get 14 from some students, because they added the sides. Ask for the perimeter and someone multiplies. The root problem is that the two measures count different things: squares inside the shape versus units along its edge. When students are handed formulas too early, they never see that difference and pick an operation at random. Grade 3 is the moment to fix this, because it is usually where area is first measured with unit squares. Students need time to cover shapes with squares, count them, and only then notice that rows times columns gives the same answer. Perimeter needs the same physical sense of walking around the edge. Compound shapes and real layouts, like a garden bed with a corner cut out, then test whether the idea is solid or just memorized.
Why it fits
How the unit builds the two ideas
The order of the unit matches how third graders come to understand measurement, and it ends with problems that check real understanding.
- Unit squares come first, so area starts as counting what covers a shape, not as a formula.
- Formulas follow the counting, so students notice that rows times columns matches their count.
- Perimeter work keeps the focus on the edge, which separates it clearly from area.
- Compound shapes ask students to split figures into rectangles, a skill that exposes rote formula use.
- Garden problems give both measures a reason: fencing needs perimeter, soil needs area.
- The answer key lets you check work fast, including multi-step compound shape answers.
Getting started
A suggested two-week run
This pacing is only a suggestion; the unit does not include a schedule. Give the unit square stage more time if your class needs it.
- Cover it with squaresBegin with the unit square pages. If you have square tiles, let students cover shapes physically before they count on paper, so area becomes something they can feel.
- Walk the edgeIntroduce perimeter as the distance around. Have students trace the outside with a finger or a marker and count units, then compare that number with the area of the same shape.
- From counting to formulasMove into the formula pages once students count reliably. Ask them to predict the area by rows and columns, then check by counting a few examples.
- Compound shapesWork through compound shapes by splitting them into rectangles. Students can color each part differently, which makes their thinking visible when you check work. Ask partners to check each other.
- Garden problems as a finaleEnd with the garden problems. Ask students to decide whether each question needs area or perimeter before they calculate, then share their reasoning with a partner.
What to buy
One unit, the bundle, or something bigger
If area and perimeter is your only gap this year, buy the Area & Perimeter unit on its own. If you will also teach place value to 1000 and fractions, or want the assessment toolkit, the Elementary Math Units Bundle at $69.99 saves $29.97 compared with buying the four units for $99.96. Upper-grade bundles in the store, such as the Algebra Foundations Bundle ($59.99, Grades 5–9), are meant for older students and are not substitutes for grade 3 measurement. TEACHMORE15 does not apply to bundles or single units.
Honest limits
Where the unit stops
The unit covers area and perimeter of rectangles and compound shapes, with unit squares, formulas and garden problems. It does not cover other measurement topics such as time, mass, volume or angles, so plan those separately. Check the content against your grade 3 requirements. Square tiles, rulers and grid paper are your own supplies. The licence covers your classroom; message Teach Lessons first if your grade-level team wants to use it together. If it does not suit your class, exchange it within 7 days for store credit of equal value.
Good to know
Frequently asked questions
Is this unit aligned to grade 3 measurement standards?
No alignment or approval is claimed. The unit belongs to a bundle written for Grades 3–5 and covers unit squares, formulas, compound shapes and garden problems. Area and perimeter are common grade 3 topics, but check the content against your own state or district standards before building your measurement unit around it.
Do students need square tiles?
The unit is printable and works without manipulatives. Tiles help many third graders at the unit square stage, so use them if your school has them. They are not part of the download. Sticky notes or paper squares cut from grid paper work as a cheap substitute, and children enjoy covering a shape on the desk before switching to the printed page.
Is it too hard for the start of grade 3?
The unit begins with counting unit squares, which most third graders can do. Formulas and compound shapes come later. If you teach it early in the year, spend longer on the counting pages and save compound shapes for later. Revisit the unit later in the year so the formula work builds on a confident start.
Can I use the garden problems as an assessment?
Many teachers use them that way, because each problem requires choosing between area and perimeter. The answer key helps you mark them. For more structured checking, the bundle's assessment toolkit adds practice and progress monitoring pages. Ask students to write one sentence explaining why they chose area or perimeter, which shows their reasoning better than the number alone.
Can I buy just this unit?
Yes. Area & Perimeter is sold on its own as well as inside the Elementary Math Units Bundle. The bundle only pays off if you will use two or more of its four units. For a third grade teacher who only needs measurement, the single unit is usually the sensible choice, and you can add the other units later.
What happens if the unit does not fit my class?
Within 7 days of purchase you can exchange it for store credit of the same value. This is store credit, not a cash refund, and you can use it on another resource from Teach Lessons. Contact Teach Lessons within that window and mention the order so the exchange can be handled.
Make area and perimeter stick in third grade
See the full unit description and the bundle option on the product page.
See the area unit →