Gallery
Discover apps people built on Collabby by chatting. Run them, then remix to make them yours.
Complex Numbers & the Complex Plane
Plot points on the complex plane and discover how multiplication rotates by adding angles and multiplying magnitudes, then draw regular polygons with powers.
Arithmetic & Geometric Sequences
Explore how terms grow using common differences and ratios, then pair the two sequences to discover a sum formula.
Sorting by Color and Shape
Color, shape, and use guide you as you drop matching items into the sparkling basket to build a group.
Conditional Probability and Bayes
Add a condition and watch the denominator shrink out of 100, then trace the probability tree backward to see whether a positive test really means disease.
Repeated and Circular Permutations
Rearrange items by hand to compare permutations with repetition, circular permutations, and permutations with repeated letters, and see how the counting rule changes.
Pascal's Triangle and the Binomial Theorem
Tap cells in Pascal's triangle to see that the entries, the right-and-down lattice paths, and the coefficients of (a+b)ⁿ are all the same combinations.
Combinations nCr
List every possible selection, divide permutations by r! to strip out order, and see the symmetry of choosing r versus leaving out the rest.
Counting and Permutations
Fill the spots one by one, multiplying the choices that remain, and count the leaves of the tree diagram to confirm the multiplication rule and n!.
Limits of Sequences and Infinite Series
Change the common ratio to see where convergence, divergence, and oscillation part ways, and find when an infinite geometric series still adds up to a finite sum.
Two-Digit Multiplication
Split two-digit numbers into tens and ones to see the four part-products, and find out why the second line of long multiplication shifts a place. 🍴 Remix it to swap the last tab's four problems for your own class's.
Order of the Day
Read the sun's position and sky color to tell morning, day, evening, and night apart, then put the day in order.
Parts and Wholes
Fill the missing piece and join the halves to figure out the whole picture from just a part.
Comparing Sizes
Pick from aligned objects to compare big and small, long and short, then tap them in size order.
Counting Fun
Tap objects one by one to count them, fill the basket to match a number, and compare which side has more.
Colors & Shapes
Tap big color dots to paint pictures, then compare colors and shapes to find the matching twin and the missing piece in repeating patterns.
Multiplying Fractions
Cut an area model across and down, count the overlapping squares, and see why multiplying fractions gives a smaller answer. 🍴 Remix it to swap the last tab's four problems for your own class's.
Multiplying and Dividing Decimals
Drop the decimal point, multiply, then put it back by counting the decimal places to discover the rules for multiplying and dividing decimals. 🍴 Remix it to swap the last tab's four problems for your own class's.
Long Division
Divide, multiply, subtract, and bring down to see where each quotient digit sits and how big a remainder can get. 🍴 Remix it to swap the last tab's four problems for your own class's.
Carrying and Borrowing
Change the two numbers and watch when the ones place forces you to carry or borrow, then solve problems column by column. 🍴 Remix it to swap the last tab's four problems for your own class's.
Probability
Put red and blue balls in the bag to name the chance in words and as 0, 1/2, or 1, then compare two bags on the same scale.
Big Numbers
Tap nine place-value slots to build huge numbers and skip-count to see which digits change as you add or subtract.
Units of Length
Read millimeter ticks by placing objects on a 20cm ruler, then see one length as mm, cm, m, and km to pick the unit that fits best.
Dividing Fractions
Count with bar models how many times a fraction fits, then multiply by the reciprocal to divide fractions.
Function Rules
Feed numbers into the rule box to find △=○×a+b, and use tables and expressions to see how two quantities correspond.