Decimals Lab Game
Free decimals game: type the decimal a shaded grid shows, pick the greater of two decimals, find one on the line, and round to the nearest tenth or whole.
Four questions about tenths and hundredths. Grid shades part of a tenths strip or a hundredths square and asks you to type the decimal it shows (a point or a comma both work). Compare puts two decimals side by side — 0.5 and 0.45, 0.08 and 0.8, 0.70 and 0.7 — and asks which is greater, or whether they are equal, the trap being that a longer decimal looks bigger. Number line marks a dot between two labeled ends with ten equal steps and asks which decimal it is. Round asks for the nearest tenth or whole, with exactly-halfway numbers rounding up. Level 1 is tenths, Level 2 hundredths with mixed-length comparisons, Level 3 adds whole parts, the equal-value traps and rounding to either place. Every answer explains the value in tenths or hundredths.
Count the shaded cells and type the decimal the grid shows.
Not a test — nothing is saved after you leave.
0.45
Ready for tenths and hundredths?
Read a grid, compare by value, find a decimal on the line, and round with the halfway mark in view.
How to use the decimals lab game
- 1Choose Grid, Compare, Number line, Round, or Mixed, and a level.
- 2In Grid, count the shaded cells and type the decimal (0.45 or 0,45 — both are read), then press Enter or Check.
- 3In Compare, tap the greater decimal or Equal; in Number line and Round, tap the right decimal out of four.
- 4Read the feedback — it says the value in tenths or hundredths and, for rounding, where the halfway mark is — then tap Next.
When this is useful
Tenths and hundredths in grade 4
Level 1 (tenths) and the hundredths grid of Level 2 are the decimal notation and comparison work of CCSS 4.NF.6–7, with the grid as the model.
Comparing by value in grade 5
Level 2's mixed-length comparisons (0.5 vs 0.45, 0.08 vs 0.8) and the equal pairs (0.70 = 0.7) target the misconception that more digits means a bigger number (5.NBT.3b).
Rounding decimals in grades 5–6
Round to the nearest tenth and whole with the halfway mark named each time (5.NBT.4), and whole parts in every question at Level 3.
Point or comma, as the class writes it
English shows 0.45; Brazilian Portuguese and Indonesian show 0,45; Spanish shows 0.45 by default with a switch to the comma for classrooms that write it, and typed answers accept either mark everywhere.
Projector rounds
A big grid or number line and large choices; the class calls the answer before you tap.
Examples to try
Grid, Level 2
45 of 100 squares shaded → 0.45 (45 hundredths).
Compare, Level 2
0.5 or 0.45? 0.5 is 50 hundredths, 0.45 is 45 hundredths — 0.5 is greater.
Number line, Level 1
A dot three steps past 2 on a line from 2 to 3 → 2.3.
Round, Level 3
12.35 to the nearest tenth: exactly on the halfway mark between 12.3 and 12.4, so it rounds up to 12.4.
Tips for better results
Say the value, not the digits
“0.45 is forty-five hundredths” beats “zero point four five”; the feedback is written that way on purpose.
Line up the places to compare
Write 0.5 as 0.50 and compare 50 with 45 — Level 2's equal pairs make the idea visible.
Grid before Compare
Reading the grid builds the value picture that comparing and rounding rely on.
Print the matching worksheet
The Decimals Worksheet Generator prints decimal arithmetic with an answer key; the Rounding generator prints decimal rounding.
How the decimals lab game works
Every decimal is stored as an exact count of tenths or hundredths, so 0.1 + 0.2 never drifts and 0.5 equals 0.50 by value. The grid shades exactly that count of cells; the number line runs ten equal steps between two labeled ends; rounding uses the classroom half-up rule, so exactly-halfway numbers round up, and about one in six rounding questions is exactly halfway.
Typed answers are read with either separator: 0.45, 0,45, .45 and ,45 all mean forty-five hundredths. The game writes decimals the way each locale does and, in Spanish, lets the viewer switch between the point and the comma; the choice is remembered on that device only.
A round is 8 questions; correct answers score 10 points plus a small streak bonus. Rounds are generated on your device and nothing is saved after you leave.
Private by design
- No account and no sign-up. Just open it and start.
- Everything runs on your device, so the decimals you type and tap during a round, and the point-or-comma preference kept on your device stays with you.
- Nothing you create is uploaded. No values, names, scores, or generated content are sent to our servers. If you're signed in, My Classeem's Recent Activity notes which tools you used — never what you did in them.
- We use Google Analytics for anonymous, aggregate measurement: page views and a few usage events, such as a worksheet being printed or a game round starting or finishing (with the mode played). It never receives what you enter — no answers, scores, names, or generated content.
Frequently asked questions
Is this decimals game free?
Yes. No account, no limit on rounds, no ads. Nothing is saved after you leave the page except the point-or-comma preference on your own device.
What grades is it for?
Level 1 (tenths) suits grade 4; Level 2 (hundredths, mixed-length comparisons, rounding to tenths) grades 4–5; Level 3 (whole parts, equal-value traps, rounding to tenths and wholes) grades 5–6.
Does it accept a comma as the decimal mark?
Yes. In every language, 0,45 and 0.45 are read as the same number when you type an answer. What the game shows follows the locale: a point in English and in Spanish by default, a comma in Portuguese and Indonesian, and Spanish has a switch to the comma.
Why does Spanish show a point by default?
Every Spanish page on Classeem writes decimals with the point, as the RAE recommends, and the Spanish worksheets this game links to print it that way. Because many Spanish-speaking classrooms write the comma, the game adds a switch, and it remembers your choice on your device.
What happens with a number that is exactly halfway?
It rounds up — 3.45 rounds to 3.5 and 3.5 rounds to 4 — the rule taught in elementary classrooms and the one the Rounding worksheet uses. The feedback says so each time.
Can I play with a keyboard only?
Yes. The grid answer is a text field that submits with Enter, and every other choice is an ordinary button reachable with Tab.
Does it work on a phone?
Yes. The grid and the number line scale to the screen, the keyboard opens in number mode, and every button is at least 44 pixels tall.
Does this use AI?
No. The numbers are generated and checked by fixed rules in your browser.
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Always free · No account needed · Nothing you type leaves your device unless you choose to save it.