Color can make useful information easier to notice and connect. Glow applies that idea through consistent number colors and a soft halo around the learning task. The best-supported foundation for lasting learning remains an attempt to recall, useful feedback, and practice spread over time. [1, 2, 4, 5]
1. What the evidence supports
A useful cue, a meaningful task, and another chance to remember.
A color cue highlights information that matters to the task. For example, keeping the same number in the same color can help a child find the selected number group. A decorative effect has a different purpose: it sets a mood or adds personality. Both can coexist, but looking appealing and producing durable learning are different outcomes.
Our working hypothesis is that a restrained, consistent visual cue can make repeated practice easier to follow and more inviting. The learner still needs to attend to the numeral, operation, letters, or sounds and produce the answer. A color should help orient attention without becoming the answer itself.
This paper brings together experimental findings about color and attention, research on recall, spacing, and beginning reading, and our application of those ideas to Glow. Each study description identifies the learners, task, and setting that produced its findings.
2. Color, attention, and memory
The meaning and placement of color matter more than simply adding more color.
Signaling across learning media [1]
Schneider et al. (2018): meta-analysis of 103 studies; 12,201 participants. Signaling included color and other cues that highlight relevant structure.
Cues highlighting relevant structure favored retention (g = 0.53; 95% CI 0.42-0.64) and transfer (g = 0.33; 95% CI 0.22-0.43).
Color links between text and diagrams [2]
Ozcelik et al. (2009): 52 undergraduates, ages 19-27, assigned to color-coded or conventional instruction on chemical synapses.
Color coding improved retention and transfer; eye movements supported easier location of corresponding text and illustration content.
Color in recognition memory [3]
Wichmann et al. (2002): five laboratory experiments using photographs of natural scenes.
Recognition benefited from natural color; changing between color and grayscale at study and test reduced performance. The benefit disappeared for falsely colored scenes.
These studies explore visual cues across different tasks and settings. Hedges g describes a standardized difference between groups; the confidence interval shows the uncertainty around that estimate.
Design interpretation: keep the cue close to the relevant symbol and repeat its meaning consistently. The selected group color can orient the learner, while readable text carries the information.
Transfer deserves special attention. A student ultimately needs to answer an ordinary printed equation or read a word in a book. We therefore recommend occasional practice on plain paper or without the familiar colored context, rather than judging mastery from performance inside a single visual format.
3. Repetition that asks the learner to think
A familiar-looking answer is not the same as an answer a student can retrieve.
Practice distributed over time [4]
Cepeda et al. (2006): quantitative synthesis of 839 assessments from 317 experiments in 184 articles.
The most effective spacing depended on the delay until the final test; longer retention goals generally called for longer gaps.
Multiplication flashcards in school [5]
Ophuis-Cox et al. (2023): 48 second graders; counterbalanced, within-student comparison; three spaced sessions per strategy.
Retrieving answers with flashcards produced greater fluency gains than chanting facts, at five minutes and one week. The time-by-strategy interaction was F(2, 94) = 15.12, p < .001, partial eta squared = .24.
Fact recall in primary school [6]
Ritchie et al. (2013): experiments enrolling 109 and 209 children, ages 8-12, learning geographical facts. The second analysis included 186 children with both follow-ups.
Retrieval benefits were observed after four days in the first experiment, with covariate adjustment, and after one and five weeks in the second.
In retrieval practice, the learner tries to produce an answer before seeing it. In restudy, the answer remains available. A useful flashcard routine is to think or say the answer first, reveal it, then compare. Tapping immediately through a deck may show all the content without providing the same opportunity to retrieve it.
Spacing means returning after a gap instead of concentrating all encounters into one sitting. Research supports distributed practice, with the spacing shaped by the learning task and how long the learner needs to remember it. [4]
Our application: invite a short, manageable return to familiar facts on later days. Give enough support for a child to succeed after an error, and revisit the item later.
4. Applying the idea to math facts
Use the glow as a place to look; use the equation as the thing to learn.
In the current math app, each number group keeps a stable hue across themes. The group numeral remains visible, and ordinary equation numerals have readable ink. A surrounding vignette echoes the group color. These implementation choices are intended to provide continuity across practice.
For a student practicing 2 x 3, the color of the 2 can identify the current group while the student works out two groups of three. On a later encounter with 2 x 4, the shared cue may help the student recognize the practice context. Objects, drawings, and explanation help the student connect that context to what multiplication means.
The same principle can accompany addition, subtraction, multiplication, and division. Keep the operation sign explicit. After an answer, a local visual response can mark the result, while written guidance communicates what to do next. Inner and outer glow feedback provides a consistent visual response during practice.
Suggested family or classroom routine: explain one example with counters, a drawing, or a number line; let the student attempt a small set; discuss an error; then return to some of those facts on another day. Mix in ordinary spoken or printed equations to check that the learning carries beyond the app.
Speed is only one possible outcome. A child who answers correctly by reasoning is showing something different from a child who guesses quickly. Practice points, streaks, and achievements help describe activity within the app. Look alongside them at accuracy, explanation, and the ability to use a skill in a new setting.
Sources: [5]
5. Applying the idea to sight words
Support attention to print, while keeping letters, sounds, and meaning central.
Beginning reading needs sound-print instruction [7]
Ehri et al. (2001): meta-analysis of 66 treatment-control comparisons from 38 experiments.
Systematic phonics instruction had an overall effect of d = 0.41 on reading compared with unsystematic or no-phonics controls.
A word read “by sight” is recognized automatically. That goal should not be reduced to remembering the color or overall silhouette of a card. For English beginning readers, instruction needs to connect print with spoken language. Color can be a supplementary aid to that work. [7]
One way an educator can use a color cue is to highlight the letter group being taught, with the complete word remaining readable. For example, a teacher might draw attention to sh in ship while saying its sound, then ask the child to blend and read the word.
Whole-card color can identify an activity or set, but should not tell the child which word to say without looking at the letters. Avoid treating every word as an unrelated colored picture. Include practice in ordinary print and short sentences, and help the student explain or use the word so that recognition connects to meaning.
Repeated attempts should follow instruction appropriate to the word and the learner. Where a spelling is unusual, explicitly teach the relevant sound-spelling relationship. If a student can name a familiar colored card but cannot read its uncolored word elsewhere, the cue has not yet led to the intended transfer.
Sources: [7]
6. Keep the cue helpful and accessible
Leave visual space around the work.
In a laboratory-classroom experiment, kindergarten children were more distracted and learned less during science lessons with heavily decorated walls than with sparse walls. This finding about classroom displays informs our preference for a calm visual setting around the learning task. [8]
Our design recommendation is to concentrate emphasis on the current task, keep decoration away from the answer, and avoid competing pulses or flashing. A child should be able to choose a comfortable theme without changing the meaning of the number colors. A neutral option is valuable when a more elaborate theme feels distracting.
Color must be redundant with readable numerals, words, symbols, and text feedback. Some users cannot reliably distinguish particular hues. As an accessibility benchmark, WCAG 2.2 requires that color not be the only visual carrier of meaning; it sets minimum text contrast of 4.5:1 for ordinary text and 3:1 for qualifying large text. These web criteria inform our design review. [9]
Evaluate contrast against the actual surface behind a character, including the brightest part of a glow. Check both appearances, large text, VoiceOver, and reduced-motion preferences. If a cue is harder to see or uncomfortable, it is not serving that learner, regardless of its visual appeal.
7. Sources and approach
The research behind the design.
This targeted narrative review was prepared on September 22, 2026. Searches used web discovery of publisher articles, PubMed/PMC records, an author-hosted paper, and the W3C standard. Search concepts included color coding and multimedia learning; signaling meta-analysis; color recognition memory; distributed practice; retrieval practice and multiplication; beginning reading and phonics; and visual distraction in children.
We selected directly relevant experiments and original quantitative syntheses, plus an accessibility standard. We checked author, year, title, and reported findings against the sources linked below. Full texts were consulted where available; some summaries rely on publisher or indexed abstracts, as identified in the reference access notes.
For families and educators, the practical conclusion is to use clear, consistent cues to support the task; give the learner a chance to retrieve; return over time; and check learning when the cue is absent. Glow applies these principles through consistent color cues and repeated practice.
References
Schneider, S., Beege, M., Nebel, S., & Rey, G. D. (2018). A meta-analysis of how signaling affects learning with media. Educational Research Review, 23, 1-24.
Read the original source ↗Publisher abstract and article preview. Original meta-analysis; signaling includes multiple cue types.
Ozcelik, E., Karakus, T., Kursun, E., & Cagiltay, K. (2009). An eye-tracking study of how color coding affects multimedia learning. Computers & Education, 53(2), 445-453.
Read the original source ↗Publisher abstract and author-hosted article proof. Randomized multimedia experiment with adults.
Wichmann, F. A., Sharpe, L. T., & Gegenfurtner, K. R. (2002). The contributions of color to recognition memory for natural scenes. Journal of Experimental Psychology: Learning, Memory, and Cognition, 28(3), 509-520.
Read the original source ↗Publisher abstract. Laboratory scene-recognition experiments.
Cepeda, N. J., Pashler, H., Vul, E., Wixted, J. T., & Rohrer, D. (2006). Distributed practice in verbal recall tasks: A review and quantitative synthesis. Psychological Bulletin, 132(3), 354-380.
Read the original source ↗PubMed abstract of the original quantitative synthesis.
Ophuis-Cox, F. H. A., Catrysse, L., & Camp, G. (2023). The effect of retrieval practice on fluently retrieving multiplication facts in an authentic elementary school setting. Applied Cognitive Psychology, 37(6), 1463-1469.
Read the original source ↗Open-access full text. Classroom experiment comparing retrieval and chanting practice.
Ritchie, S. J., Della Sala, S., & McIntosh, R. D. (2013). Retrieval practice, with or without mind mapping, boosts fact learning in primary school children. PLOS ONE, 8(11), e78976.
Read the original source ↗Open-access full text via PMC. Two classroom experiments with geographical facts.
Ehri, L. C., Nunes, S. R., Stahl, S. A., & Willows, D. M. (2001). Systematic phonics instruction helps students learn to read: Evidence from the National Reading Panel’s meta-analysis. Review of Educational Research, 71(3), 393-447.
Read the original source ↗Publisher abstract of the original meta-analysis of systematic phonics instruction.
Fisher, A. V., Godwin, K. E., & Seltman, H. (2014). Visual environment, attention allocation, and learning in young children: When too much of a good thing may be bad. Psychological Science, 25(7), 1362-1370.
Read the original source ↗Publisher and PubMed abstracts. Laboratory-classroom experiment with kindergarten children.
World Wide Web Consortium. (2024). Web Content Accessibility Guidelines (WCAG) 2.2. W3C Recommendation, December 12, 2024. Success Criteria 1.4.1 and 1.4.3.
Read the original source ↗Primary accessibility standard used as a design benchmark.