Homeschool Testing: CAT vs Iowa Test and What Actually Works
A practical comparison of the CAT, Iowa Test, Stanford 10, MAP Growth, and other standardized tests for homeschoolers: side-by-side breakdown, administration walkthrough, grading deep dive, and how to choose the right one.
Every spring, homeschool parents Google the same things: "CAT vs Iowa Test." "Do I even need to test?" If that's you, I want to walk through what the options actually are and which one makes sense for your family, from one homeschool mom to another.
This year the question feels more real for me. My twin 5-year-olds are entering their first testing year, which means I'll be managing testing for three kids at once. Digging into every detail for my own household made me want to put it all in one place.
A quick note: I'm not a testing expert or attorney. Always verify your state's current requirements before purchasing.
Does Your State Even Require Testing?
Most states do not require standardized testing for homeschoolers. Texas, Illinois, California, and many others leave it optional. But several do:
- Pennsylvania: grades 3, 5, 8, and once in high school (portfolio review is an alternative)
- New York: annual assessments
- Florida: annual evaluation (standardized testing is one approved option)
- Arkansas, Minnesota, Ohio, Maine, Georgia: annual testing at specified grades
Virginia, where we live in Stafford, requires evidence of progress by August 1. Options include a standardized test, portfolio evaluation, or correspondence school report card. The test benchmark is a composite score at or above the 23rd percentile (4th stanine), an intentionally achievable bar.
Most states with testing requirements say "any nationally normed standardized achievement test." Both CAT and Iowa qualify. States that maintain specific approved lists tend to include both. The HSLDA website has a current state-by-state breakdown worth bookmarking.
The Big Two: CAT and Iowa Test
CAT vs Iowa: Complete Side-by-Side Breakdown
Grades available:
- CAT: Online starts at grade 2. Paper (TerraNova CAT 6) starts at kindergarten, homeschool-tested at the K level, oral-based, about 1.5 hours. If you need online testing for K-1, look at Iowa online or MAP Growth K-2.
- Iowa: K-12 for both paper and online.
Time:
- CAT: ~1.5 hours for K, scaling to ~5 hours upper grades. CAT E Survey (short form) takes ~2.5 hours for grades 4-12.
- Iowa: 3-5 hours total, typically spread over 2-3 days in morning sessions.
Timed vs untimed:
- CAT online: Untimed option available, one of the biggest practical differences.
- Iowa: Strictly timed. Every section has a fixed limit.
Administrator qualifications:
- CAT: No degree required. Paper version needs a test agreement form; online has no supervision requirements at all.
- Iowa paper: Bachelor's degree required plus tester certification from the provider.
- Iowa online: The testing company administers (reads directions, times sections, manages the platform). You supervise, quiet environment, on-task, bathroom breaks. No degree required.
Subtests:
- CAT: Broader categories, reading, language arts, math, science, social studies.
- Iowa: Finer granularity. In math alone: computation, concepts, problem solving, data interpretation. Language arts: vocabulary, comprehension, spelling, capitalization, punctuation, usage/expression.
Scoring detail:
- CAT: Percentile rank, stanine, and grade equivalent.
- Iowa: All of the above plus subtest-level breakdowns and a Lexile measure (Form E) that maps to book-leveling systems, genuinely useful for curriculum planning.
Group testing:
- CAT E Survey: Grades 4-12 can test together in one session.
- Iowa: Grades 3-8 together, 9-12 together.
Cost:
- CAT: $25-60 per student.
- Iowa: $45-80 per student. Online is typically cheaper than paper.
Where to buy:
- CAT: Christian Liberty Press, Seton Testing Services, Academic Excellence Testing Services, BJU Press (TerraNova CAT 6)
- Iowa: Seton Testing Services, BJU Press Testing & Evaluation, Abeka Testing
California Achievement Test (CAT)
The CAT is the shorter, simpler, more flexible option, a norm-referenced test giving you a percentile rank. If you need to satisfy state requirements efficiently, this is it.
Test forms:
- CAT E Survey (grades 4-12): Shortest version. Most families use this for straightforward compliance.
- TerraNova CAT 6 Complete Battery (grades K-12): Full-length, more data than the Survey.
- TerraNova CAT 6 Basic Battery (grades K-12): Reading and math only. Verify state acceptance.
- CAT Plus: Supplemental subtests for word analysis, vocabulary, and language mechanics.
Format: Multiple choice only. Online version is untimed; paper versions are timed but shorter than alternatives. No degree required to administer.
Iowa Test of Basic Skills (ITBS)
The Iowa is the thorough, detailed option. If the CAT is a snapshot, the Iowa is a full portrait. Families choose it when they want data to drive curriculum decisions, not just a compliance checkbox.
Test forms:
- Form E (2018): Current version. Full-color, shorter times than older Form C, more accessible for ELL students.
- Form C (2008): Still available but rarely needed over Form E.
- Complete Battery: All subtests at full length, gives you detailed subtest breakdowns.
- Survey Battery: Abbreviated, like the CAT E Survey. Less common.
Format: Primarily multiple choice with some reference-format questions at upper levels (charts, maps, data interpretation). Timed. 3-5 hours across multiple days.
Other Testing Options
Stanford 10: Most comprehensive, untimed, mixed question formats including some open-ended. Takes longer than CAT or Iowa. Bachelor's degree required for paper; online version available.
MAP Growth: Online, untimed, fully adaptive, questions adjust in real time to find your child's exact instructional level. K-2 version has built-in audio for pre-readers. Excellent for kids who don't fit neatly into grade-level testing.
Woodcock-Johnson IV / Peabody: Oral tests administered one-on-one by a trained examiner. No reading, no bubbles, no clock. Takes 60-90 minutes. Most natural format for young children or test-anxious kids. Cost: $75-150+ per student.
What to Expect: Administration Walkthrough
Ordering
- Pick your provider, select grade level, choose your form. When in doubt for compliance, Survey is fine.
- Paper tests: order 2-3 weeks ahead. Online: access is typically immediate or within a day.
- Read the administration manual cover to cover before test day. It gives you an exact script, say it exactly.
Setting Up the Testing Environment
Location: Quiet room with a door that closes. Not the kitchen table.
Materials: Sharpened #2 pencils (at least 3), blank scratch paper, timer (phone on Do Not Disturb), water bottle, tissues.
Remove: Wall posters with math facts, maps, spelling words, anything a child could reference.
Test Day: What to Say (and Not Say)
Say: "This helps us see what you've learned and what to work on next. Some questions will feel easy, some hard, just do your best. You won't know every answer, that's fine."
Don't say: "Don't worry, it's easy." "I need you to do really well." Anything comparing siblings. "This determines whether you move up."
During the Test
Follow the script exactly. Don't rephrase directions. Set your timer to the exact minutes specified. When time is called, pencils down, no extra time. Bathroom breaks between sections only. If they freeze: "It's okay to pick your best answer and move on."
After the Test
Paper: mail the answer sheet within a day or two. Online: confirm submission before closing. Results: paper takes 2-4 weeks; online CAT is 1-5 days; Iowa online is 1-2 weeks; MAP Growth is often instant.
Reading the Score Report
Key metrics:
- National Percentile Rank (NPR): The headline. 68 means better than 68% of same-grade students. 25th-75th is the broad middle.
- Stanine: 1-9 scale. 4th stanine (23rd-39th percentiles) is the common state threshold.
- Grade Equivalent (GE): Most misunderstood. A 3rd grader with GE of 5.3 scored as well on the 3rd grade test as an average 5th grader would, it doesn't mean they're doing 5th grade work.
- Lexile (Iowa Form E): Maps to book difficulty for independent reading picks.
When numbers disagree: A high GE with a middling percentile is common, the percentile tells the real story. A split (85th in reading, 30th in math) is actually the most useful result: it tells you exactly where to focus next year. Most state thresholds are at the 23rd percentile composite, a deliberately low bar designed to flag kids needing intervention, not punish normal variation.
How to Decide
Answer these honestly rather than chasing the "best" test in the abstract:
- Administer yourself or delegate? CAT works for everyone. Iowa online lets the company handle it while you supervise. Oral tests delegate completely.
- Can your child handle a timed test? If no: CAT online (untimed), MAP Growth, Stanford 10, or oral tests.
- Strong enough reader? For pre-readers: MAP Growth K-2, Woodcock-Johnson, Peabody, or paper TerraNova CAT 6 K level. See my kindergarten and first grade testing guide for more.
- How many kids? CAT E Survey groups grades 4-12. Iowa groups 3-8 and 9-12. Stagger across days if needed.
- Compliance or information? Compliance: CAT is cheaper and easier. Curriculum planning: Iowa or MAP Growth give more to work with.
- What does your state accept? Verify before purchasing.
A Practical Note About Test Anxiety
A first standardized test often measures test-taking unfamiliarity as much as knowledge. Do a practice run. If the score is lower than expected, consider that the format may be the issue. Try a different format next year, an oral test can reveal a very different picture than a bubble sheet. For significant anxiety, the extra cost of Woodcock-Johnson or Peabody is worth it for results that reflect what your child actually knows.
Frequently Asked Questions
The Short Version
Simple compliance: Get the CAT. $25-60, no degree required, untimed online option, fast results.
Curriculum planning: Iowa or MAP Growth give detailed diagnostic data but cost more and take longer.
Test anxiety or pre-reader: Woodcock-Johnson or Peabody, oral, one-on-one, worth the cost.
New to homeschooling? Start with getting started with homeschooling. For supplies, here's what my family actually uses.
None of these tests define your child or your homeschool. They're one data point on one day. Get the information you need, file the paperwork, and get back to the actual work of learning together.
This post is a personal overview based on research and experience, not professional or legal advice. State testing requirements change. Always verify your state's current laws and approved test list before purchasing.
