Research
Why This Works
Third Grade is built on what research says helps children learn. Here is what each part of the program does, and the evidence behind it.
These features are based on published research and federal practice guides. Third Grade itself has not been tested in a controlled study, so we describe it as research-based, not proven. Where the evidence for a feature is thin, we say so.
Daily "Remember?" review
What we do
Math and ELA lessons open (once the boxes are on the day pages) with three quick questions on skills taught at least a week earlier. The questions come back again and again, spread across the whole year, and the answers are checked the same day.
What the research says
Spacing practice out over weeks and months, rather than practicing a skill once and moving on, helps learners remember it longer. A federal research panel recommends planning review of key content after a delay of several weeks to several months.
Sources
Recalling, not rereading
What we do
The Remember? boxes, exit tickets and weekly checks ask your child to pull answers out of memory, with no notes or old pages open, and then get the right answer right away.
What the research says
Short quizzes that make learners recall key content help them learn it; the federal panel rated this recommendation as having strong evidence. In a classroom study with 48 second graders, practicing multiplication facts by recalling them with flashcards built more fluency, a week later too, than chanting the facts aloud.
Caution: Most of this research was done with older students. We keep the review short and low-stakes, and we give the answer straight away so a wrong answer is not practiced.
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Worked examples, then practice
What we do
New math skills start with a worked example: in the Mini-Lesson, and again in the Look box on the practice page. Then your child tries similar items alone, and the guided and independent practice go back and forth between examples and problems.
What the research says
Alternating between studying a worked-out solution and solving a problem alone helps students learn, especially early on. The same panel also recommends connecting concrete examples with abstract ideas, as the lessons do when they move from blocks and drawings to numbers.
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Fractions on a number line
What we do
Unit 4 starts fractions with equal shares, then places them on a number line, including fractions greater than 1. Children use number lines to find equivalent fractions and to compare fractions, and measure to the half and quarter inch.
What the research says
Federal practice guides recommend helping children see that fractions are numbers with a place on the number line, and using the number line to teach math concepts to children who struggle. In a pilot study with struggling fifth graders, lessons that used the number line together with concrete materials showed promise for building fraction understanding.
Caution: The pilot study was small and with older students. We use the number line alongside fraction strips and drawings, not instead of them.
Sources
- Siegler et al. (2010). Developing Effective Fractions Instruction for Kindergarten Through 8th Grade. IES Practice Guide.
- Fuchs et al. (2021). Assisting Students Struggling with Mathematics: Intervention in the Elementary Grades. IES Practice Guide (WWC 2021006).
- Schumacher, Jayanthi, Gersten, Dimino, Spallone & Haymond (2018). Learning Disabilities Research & Practice, 33(4), 192-206.
Fact strategies before speed
What we do
Multiplication facts are taught in families (×2, ×5 and ×10, then ×3, ×4 and ×6, then ×7, ×8 and ×9), each with a strategy: doubles, skip-counting, and building a new fact from one your child already knows. Speed comes afterward, through short daily practice, Remember? boxes and games.
What the research says
A federal panel on helping students who struggle in math recommends systematic instruction that builds understanding, and regular timed activities as one way to build fluency. A district study compared one school that added daily 10-minute fact drills with two similar schools. The authors cautioned against assuming the drills were what helped, and they favored fluency built on properties and strategies. Recall practice, rather than chanting, also builds fluency (see Recalling, not rereading).
Caution: The district study was correlational, not an experiment. If you use timed practice at home, keep it short and have your child beat their own score, not race anyone else.
Sources
- Fuchs et al. (2021). Assisting Students Struggling with Mathematics: Intervention in the Elementary Grades. IES Practice Guide (WWC 2021006).
- McGee, Richardson, Brewer, Gonulates, Hodgson & Weinel (2017). School Science and Mathematics, 117(6), 259-268.
- Ophuis-Cox, Catrysse & Camp (2023). Applied Cognitive Psychology, 37(6), 1463-1469.
Problem structure, not keywords
What we do
Word problems are taught by their structure: equal groups, sharing, grouping, comparing, and two-step problems with a letter for the unknown. Children draw the problem first, and the lessons do not teach "clue words".
What the research says
Reviews find that teaching children to recognize the type of a word problem and use a plan or diagram that matches it improves word-problem solving for elementary students who struggle in math. Keyword tricks fail often: an analysis of word problems on state tests found that a keyword strategy would work for fewer than half of the one-step problems and fewer than 10% of the multistep problems, and a study of third graders found that keywords like "more" mislead children when the word does not match the operation. A federal panel recommends deliberate instruction on word problems.
Sources
- Powell (2011). Learning Disabilities Research & Practice, 26(2), 94-108.
- Hardy, Douglas, MacLean, Mason & Powell (2025). How keywords impact word-problem performance: When "more" does not mean to add. Learning Disability Quarterly.
- Fuchs et al. (2021). Assisting Students Struggling with Mathematics: Intervention in the Elementary Grades. IES Practice Guide (WWC 2021006).
Word study with word parts
What we do
Each week's word study teaches one spelling pattern with a rule, a sort and a dictation sentence. The year moves from syllable types to prefixes, suffixes and spelling changes, so children read and spell longer words by their parts and use those parts to work out meanings.
What the research says
A federal panel found strong evidence for teaching children to decode words, analyze word parts, and write and recognize words. A research synthesis found that teaching morphology (roots and affixes) can help word reading, spelling and vocabulary.
Caution: The morphology synthesis included only seven studies, with a wide range of results. We teach word parts as part of a full reading program, not on their own.
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Reading About Our World
What we do
Each week has an original nonfiction passage about that week's science or social studies topic, with a word box and four questions, so reading and the content subjects build the same knowledge.
What the research says
What a reader already knows about a topic plays a large part in understanding a text about it. Researchers call for building content knowledge inside reading instruction in the early grades, and summaries of comprehension research list vocabulary and knowledge building among the supports for comprehension.
Caution: The research base for knowledge-building programs is growing but still young. Gains build over years, not weeks.
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Writing taught step by step
What we do
Children learn to plan, draft, revise and edit opinion essays, narratives, poems and a research report, using model texts, planning frames and checklists. Lessons also teach sentence building, such as combining short sentences, alongside spelling and handwriting.
What the research says
A federal panel found strong evidence for teaching students to use the writing process for a variety of purposes, and moderate evidence for teaching sentence construction, spelling and handwriting until they are fluent.
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Talk about texts and ideas
What we do
Lessons build in discussion: questions with no single right answer, "What in the text makes you think so?", partner talk, reader's theater and presenting research to an audience.
What the research says
A federal panel recommends guiding students through focused, high-quality discussion of what a text means. A research summary lists discussion and analysis of text among the ways to strengthen reading comprehension.
Caution: The panel rated the evidence for this recommendation as minimal, meaning it rests on expert judgment more than on strong studies.
Sources
The engineering design process
What we do
Science includes design challenges: a device that uses magnets to solve a problem, and a weather instrument children build, test and improve. Children define the problem, plan, build, test, compare designs and record what they learn.
What the research says
In a large randomized trial in 604 elementary classrooms, students using an engineering curriculum built around design challenges outperformed comparison students in both engineering and science learning. Another study with third and fourth graders found larger science gains in most of the units taught with engineering design challenges than with the usual curriculum, and a study with third graders found that writing about design work helped them learn engineering ideas.
Caution: These studies tested specific curricula with trained teachers. Our design challenges follow the same steps, but they have not been tested themselves.
Sources
Questions, sources and civic action
What we do
Social studies follows the inquiry arc: each lesson opens with a big question, children work with sources such as maps, photos and short documents, and they back their answers with evidence. The year ends with the Civic Action Project, in which children research a real community issue, plan and take a safe action, and present what happened.
What the research says
A federal panel recommends prompting students to ask and answer deep explanatory questions, such as why, how and what if, because explaining ideas helps learning.
Caution: We did not find a verified study of the full inquiry arc or of civic action projects with third graders, so this part rests mainly on the C3 Framework and on the general research about explanatory questions.
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Weekly checks with clear next steps
What we do
Every Friday check names its "I can" goals and gives three routes: move on, practice the skill a new way, or reteach the named days. Unit tests name the exact weeks and days to reteach for each section.
What the research says
Federal panels recommend making assessment results part of an ongoing cycle of teaching (check, decide, reteach and check again), helping students look at their own results and set goals, and using quizzes to find what still needs to be learned.
Caution: The panels rated the evidence for these recommendations as minimal. What matters most is what you do after a check, not the check itself.
Sources
Home Connection sheets
What we do
Each week has a one-page Home Connection sheet with the week's big ideas, plus a short activity and a talk question for each subject, using things you have at home.
What the research says
Federally funded guidance for families says that continued family support for reading throughout elementary school helps children's reading, and gives short home activities for families to practice skills together.
Caution: This guidance offers practical activities rather than new studies, and our sheets have not been tested on their own. Treat them as a simple way to keep learning going at home.