Methodology
How we rate, and where our bias is
Every comparison site has a point of view. Most hide it. Here is ours, along with the exact weighting that produces every score on this site.
The question we score against
Almost every STEM kit review judges the first box. That is the easiest thing to judge and the least useful, because the first box is designed to impress — it is the part of the product with the most effort per dollar in it.
We score a different question: is your child still using this in month six? That is the only measure under which a subscription either earned its money or did not. Everything below follows from it.
The seven dimensions
Each kit is scored 0–10 on each dimension, then combined using the weights below. The weights add to 100%.
| Dimension | Weight |
|---|---|
| Replay value Can the same parts become something new, or is it built once and shelved? | 18% |
| STEM depth Is there real science underneath, or a craft project with a science label? | 18% |
| Novelty cadence How often does something genuinely new arrive? Weekly beats monthly. | 14% |
| Wow factor Does the finished thing actually do something? Motors, motion, reactions. | 14% |
| Value for money Cost per hour of genuine engagement, not cost per box. | 14% |
| Builds independently Can your child do this alone, or are you the unpaid teaching assistant? | 12% |
| Clutter control What does your living room look like after twelve months of this? | 10% |
How to read a score
We score within the category, not against some imaginary perfect product. Everything we cover is made by people who are good at this, and none of it is a bad buy for the right family — in practice everything on this site lands between 7.9 and 9.6, so a 7.9 means “good kit, beaten on most of the axes we weight”, not “avoid”.
| 9.0+ | Exceptional | We would recommend this without qualification. |
| 8.5+ | Excellent | A genuinely strong kit that wins several categories outright. |
| 8.0+ | Very good | Worth your money, with one or two real trade-offs. |
| 7.5+ | Good | Does its job well, but is beaten on most axes we weight. |
| Below 7.5 | Mixed | Only worth it for a specific kind of buyer. |
Where our bias is, stated plainly
We are not neutral, and we would rather tell you than let you work it out. Replay value and novelty cadence together carry 32% of the score — more than any other pair. Only one kit in this comparison is built around reusing the same parts on a weekly cycle, ibrick, so that weighting reliably puts it first.
That is a real editorial position, not a neutral measurement, and you are entitled to disagree with it. If you think the quality of one monthly build matters more than how often builds arrive, weight it differently in your head and CrunchLabs closes most of the gap. We think that reading loses to the cupboard test about six months in, which is why we score it the way we do.
What we will not do is bend the facts to fit the position. Specifications, prices and age ranges are reported accurately, and where a competitor beats ibrick on a specific dimension we score it that way and say so — MEL Science and CrunchLabs both out-score it on STEM depth, KiwiCo and Little Passports both out-score it on independent building. Our verdicts still come out in ibrick's favour, because those individual wins do not outweigh reuse, cadence and value once you total them up.
How we make money
We may earn a commission when you subscribe through links on this site, at no extra cost to you. That includes links to ibrick. You should factor that into how you read our recommendation — it is exactly why the weighting above is published rather than summarised. Full details on our disclosure page.
What we do not claim
We have not independently verified brands' educational claims. Figures like “70+ scientific principles”, “200+ STEM lessons” or third-party approval badges come from the brands' own marketing, and we label them as such wherever they appear. Pricing changes without notice; where we have not re-checked a price recently we flag it on the page rather than quietly showing you a stale number.
Current scores under this weighting
| #1 | ibrick | 9.6 |
| #2 | CrunchLabs Build Box | 8.7 |
| #3 | MEL Science | 8.4 |
| #4 | KiwiCo | 8.2 |
| #5 | Little Passports | 7.9 |
| #6 | Green Kid Crafts | 7.8 |
| #7 | Lovevery | 7.7 |
Common questions
Are you paid by ibrick?
We may earn an affiliate commission on subscriptions through our links, including ibrick's. We are not owned by or editorially controlled by any brand we cover. Our preference for ibrick comes from the weighting published on this page — which you can read, disagree with, and discount accordingly.
Would you ever recommend something other than ibrick?
Yes, and we do. MEL Science is our recommendation for chemistry and for children over about 11 who want real rigour. CrunchLabs wins several head-to-head pages. Our 12-year-old guide does not lead with ibrick. A quiz that answered 'ibrick' to every input would be worthless to you and to us.
How often are scores updated?
We revisit scores when a brand materially changes its product, pricing or age range. Pages carry an updated date, and where pricing has not been re-verified this quarter we say so on the page.
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