Dice Roller

How to Roll Dice for a Class Game

To use the dice roller above, choose how many dice and which kind, press Roll or the Space bar, and read the faces and the total from across the room. At Chalkbox, we build free classroom tools, and this one runs in the browser with no account and nothing to install.

1. Set the number of dice. "Number of dice" goes from 1 to 6 and starts at 2.
2. Pick the kind of dice. "Kind of dice" offers d4, d6, d8, d10, d12 and d20. The number is the count of sides, so a d6 has 6 sides and a d20 has 20. The roller starts on d6.
3. Roll. Press the Roll button, the Space bar or the R key. The dice shake for about 0.6 seconds and then land.
4. Read the result. With 2 or more dice, the line under the dice reads "Total:" and the sum. With one die, it reads "Rolled:" and the number.
5. Press Fullscreen. The dice, the total and the Roll button fill the screen for the projector.

Take two six-sided dice as an example, written 2d6. If they land on 3 and 5, the line under the dice reads "Total: 8", and "Last rolls" adds the line "2d6: 3 + 5 = 8". Six-sided dice show dots (pips) like real dice.

The other kinds show the number on each die, with a small label such as "d20" in the corner. "Last rolls" keeps the 10 most recent rolls, and "Clear list" empties it between games. The list is gone once the page is closed, so copy down any roll you need before you close the tab.

The Space bar and the R key only roll when the cursor is not in a box or on a button. With the computer's "reduce motion" setting on, the dice land at once with no shaking.

The roller remembers the number and kind of dice in this browser. Nothing is sent to a server.

Which Dice to Use for Classroom Games

The right kind of dice depends on how many outcomes your activity needs. Every face has an equal chance on every roll, so a die with N sides gives each face a 1-in-N chance.

A few ways to put each kind to work:

• d6 for board-style games and turn order. Each team rolls one d6 at the start, and the highest roll goes first. Re-roll any tie. For moving pieces on a paper game board, roll one or two d6.
• d20 for a numbered list. Number 20 review questions on a slide, roll one d20 and answer the question that matches. Each question keeps its 1-in-20 chance on every roll, so a number can come up twice. Cross off used numbers and re-roll a repeat.
• d10 and d12 for shorter lists. Match the die to the length of your list. If the list has 9 or 15 items, re-roll any number past the end, or put the items on the wheel spinner instead.
• d4 for small choices. Number four corners of the room or four groups, then roll to send the class to one of them.
• d6 for number practice. Roll two or three d6 and have students add, subtract or multiply the faces. For a printed set of practice problems, use the math worksheet generator.

The total range grows with the number of dice. Six d6 give totals from 6 (six 1s) to 36 (six 6s), and six d20 give totals from 6 to 120 (6 × 20).

Using the Dice Roller in a Team Review Game

The dice roller adds chance to a team review game by deciding either how many points a question is worth or which question a team answers. Pick one use per game and announce it before the first roll.

• Roll for points. A team answers a question, and if the answer is correct, it rolls one d6 and earns 1 to 6 points. Switch to 2d6 for a range of 2 to 12 points on harder questions.
• Roll for the question. Number your questions, set the die that matches the list, and have the team roll for the question it answers.
• Roll for turn order. Each team rolls one d6 at the start, and play goes from the highest roll to the lowest.

The dice roller does not keep score, so keep points on the classroom scoreboard in a second browser tab. For rounds where teams race to answer first, open the classroom buzzer in a third tab. To build a board of questions by category and point value, use the review game board maker.

Settle Disputes with Last Rolls

"Last rolls" lists the 10 most recent rolls, e.g. "2d6: 3 + 5 = 8". If a team says it rolled an 11, point to the line on the screen and move on. Press "Clear list" at the start of each game so old rolls do not mix with new ones.

If you still need teams, the team name generator gives each group a name before the first roll. More game formats are on the classroom games page.

Probability Lessons with Two Six-Sided Dice

Two six-sided dice give totals from 2 to 12, and 7 is the most likely total because 6 of the 36 equally likely results add up to 7. Each die has 6 faces, so two dice have 6 × 6 = 36 ordered results. "Ordered" means a 1 on the first die and a 6 on the second counts as a different result from a 6 then a 1.

Add the Ways column to check the table: 1 + 2 + 3 + 4 + 5 + 6 + 5 + 4 + 3 + 2 + 1 = 36. Students can build this table themselves by listing every pair before they look at the answer.

Seven comes up most because every number on the first die has a partner on the second die that makes 7: 1 and 6, 2 and 5, 3 and 4, and so on up to 6 and 1. A total of 2 needs a 1 on the first die, and a total of 12 needs a 6 on the first die, so each has only one pair.

A Tally Experiment for the Class

A tally experiment lets students compare real rolls with the 6-in-36 chance of a 7.

1. Set the dice roller to 2 dice, kind d6.
2. Draw a tally chart with a column for each total from 2 to 12.
3. Roll 72 times and mark one tally per roll. "Last rolls" only holds 10 rolls, so tally each total as it lands.
4. Compare the 7 column with the expected count. A 6-in-36 chance over 72 rolls works out to 72 × 6 ÷ 36 = 12 sevens.

The counts may not match the table exactly, because each roll is random. Ask students why their 7 column landed above or below 12, and whether 2 and 12 came up least. For a one-die version, roll a single d6 60 times: each face has a 1-in-6 chance, so 60 ÷ 6 = 10 of each face is the expected count.

How the Dice Roller Keeps Every Roll Fair

Every face has an equal chance on every roll of the dice roller, so there is no bias toward any face. The dice roller picks each face with the browser's built-in cryptographic random number generator.

A few of the values that generator can produce would make some faces slightly more likely. The roller throws those values away, so each face of a d4, d6, d8, d10, d12 or d20 keeps the same chance.

The same equal chance holds on every roll, which makes a useful class discussion. A 6 on the last roll does not make a 6 more or less likely on the next roll. If students think a number is "due", the tally experiment above lets them test that idea with their own counts.

What the Dice Roller Does Not Do

The dice roller rolls 1 to 6 dice of one kind and shows the faces and the total, and it does not add modifiers, mix kinds in one roll, keep score or play sound. Each gap has a simple fix:

• Modifiers. The total is the plain sum of the faces. If your game adds a bonus, such as +2 for a hard question, add it aloud or on the scoreboard.
• Mixed kinds. All dice in one roll are the same kind. To roll a d6 and a d20, roll twice: set d6 and roll, then switch to d20 and roll.
• More than six dice. Roll twice and add the two totals.
• Score. Keep team points in the scoreboard tab or on the whiteboard.
• Sound. The roller is silent, so read each total aloud for students who cannot see the screen.
• History after closing. "Last rolls" clears when the page closes, so write down any roll you want to keep.
• Picking names. A die only gives numbers. To pick a student, put names on the wheel spinner so you do not have to number the class list first.

To start, set the number and kind of dice, press Fullscreen and press Roll on the dice roller above.