Grades 5-6 mathematics
Step 3 covers Grades 5-6. All 36 activities for this grade band are now translated into English, with the same quizzes and best-score tracking as the Korean site.
🔢 Number & operations
Mixed Calculation Lab
Check step by step which comes first — parentheses, multiplication/division, or addition/subtraction.
Open English lesson → 🔼Number Ranges & Rounding
Pick a reference number and an inequality, then compare rounding up, down, and to the nearest.
Open English lesson → 🔗GCD & LCM Lab
Enter two numbers and spot the overlap in their multiple lists.
Open English lesson → ▦Finding Divisors Lab
Enter a number and see every divisor laid out as a rectangle array.
Open English lesson → 🪣Water Jug Puzzle
Fill, empty, and pour between a few jugs to hit an exact target amount.
Open English lesson → 🍕Simplifying & Comparing Fractions
Drag a slider and watch simplifying and finding common denominators play out as bar diagrams.
Open English lesson → ✖️Decimal Multiplication & Division
See decimal multiplication on a 100-square grid, then scale both numbers by 10 to turn division into whole numbers.
Open English lesson → 🍕Fraction Multiplication & Division
See fraction multiplication with a grid model, then explore why dividing means multiplying by the reciprocal.
Open English lesson → ➕Fraction Addition and Subtraction Lab
Use a bar model to see how to add and subtract two fractions with different denominators by finding a common denominator.
Open English lesson → 🔀Fraction and Decimal Relationship Lab
Use the sliders to see how a fraction changes into a decimal and confirm that they point to the same position on the number line.
Open English lesson → ➗Fraction Division Reasoning Lab
Understand why dividing by a fraction means multiplying by its reciprocal, starting with the original meaning of division.
Open English lesson → 🧩GCD and LCM Relationship Lab
Explore the surprising relationship that the product of two numbers is always equal to the product of their GCD and LCM.
Open English lesson → ➗Euclidean Algorithm Lab
Explore the 2,300-year-old Euclidean algorithm for finding the greatest common divisor of two numbers using repeated division, with step-by-step calculations and…
Open English lesson →📈 Patterns & relationships
Corresponding Quantities Lab
See two quantities change together as a matched pair, in a table and a graph.
Open English lesson → ⚖️Ratio & Proportion Lab
Use a map scale and a sugar-water mixture to see how a ratio stays constant.
Open English lesson → 📊Proportions & Proportional Division Lab
Set up a proportion to find an unknown value, and split a whole by a given ratio.
Open English lesson → ⚙️Input-Output Machine Lab
A mysterious machine outputs a different number according to a fixed rule. Look at a few examples, find the hidden rule, and predict the next result.
Open English lesson →📐 Shape & measurement
Symmetry & Congruence Lab
Mirror a shape or rotate it 180° to check line symmetry and point symmetry.
Open English lesson → 🎁Rectangular Prism Parts Lab
Count a box's faces, edges, and vertices one by one to see its basic structure.
Open English lesson → 🔻Prisms & Pyramids Lab
Change the number of sides on the base and watch the face, edge, and vertex counts shift.
Open English lesson → 🥫Cylinders, Cones & Spheres Lab
Tap through three round solids and compare their parts and nets.
Open English lesson → 🎲Counting Unit Cubes Lab
Count how many blocks are stacked in a picture to build up spatial reasoning.
Open English lesson → 📐Geoboard Area Puzzle
Connect dots to build a shape and count grid squares to hit a target area exactly.
Open English lesson → 📐Triangle Base & Height Lab
Slide the vertex to build acute, right, and obtuse triangles, and confirm the area always matches.
Open English lesson → ◯Pi & Circumference Lab
Roll a circle and see for yourself how many diameters it travels.
Open English lesson → 🍕Circle Area Lab
Cut a circle into pizza-slice wedges and rearrange them into a rectangle to see the area formula.
Open English lesson → 🧱Rectangular Prism Surface Area & Volume Lab
Adjust length, width, and height with sliders and unfold the net to see surface area and volume change.
Open English lesson → 📐Cube Net Lab
Fold a net in a 3D viewer and compare all 11 arrangements that really make a cube.
Open English lesson → 👁️Block-Building: Top, Front & Side Views Lab
Look at block structures and identify their front and side views to develop your spatial sense of solid shapes.
Open English lesson → 🥧Archimedes' Method for Calculating Pi
Experience Archimedes' method of narrowing the range of pi by drawing regular polygons inside and outside a circle and continually increasing the number of sides.
Open English lesson → ⚖️Centroid Finder Lab
Move the vertices of a shape yourself to see how its centroid is calculated, then use the hanging method to check that it matches the actual balance point.
Open English lesson →📊 Data
Mean, Median & Mode Lab
Type in your own numbers and see how the mean, median, and mode each shift.
Open English lesson → 🎲Coin & Dice Simulator Lab
Increase the number of trials and watch the results settle toward the true probability.
Open English lesson → 🥧Pie Chart Lab
Adjust each category's count with sliders and watch the wedge size (percentage, angle) change.
Open English lesson → 📊Strip Graph Lab
Change how many people chose each item and watch the length it takes up in the strip change with it.
Open English lesson → 🎯Buffon’s Needle Lab
Try a famous 18th-century probability experiment: throw a needle hundreds of times onto lined paper and estimate π using only the probability that the needle crosses…
Open English lesson →