Arithmetic
Arithmetic: 14 free interactive math resources. Practice core operations and quantity models — fractions, percents, area.
Guide
About this topic
Arithmetic builds part–whole intuition with fraction bars, percentages, and ratios — bridging primary to secondary.
What you learn
- Fraction meaning and comparison
- Percentages and ratios
- Quantity models
- Foundation for algebra and stats
Subtopics
Key formulas
a/bpercent = part/whole × 100%
FAQ
Which grades?
Upper primary through early secondary review.
How does this differ from statistics?
Arithmetic models quantities; stats describes data sets.
Useful for remediation?
Yes — dragging models beats algorithm-only drills.
Resources in this topic
14 free interactive resources in 3 groups
Fractions & percents
- Activity
Meaning of a fraction
Split a unit into n equal parts and take m of them: m/n.
Guide - Activity
Adding like fractions
Same denominator: keep it, add numerators. a/n + b/n = (a + b)/n.
Open - Activity
Adding unlike fractions
Different denominators: find a common denominator, then add.
Open - Activity
Percents
A percent treats the whole as 100 parts — “how many per hundred”.
Guide - Activity
Ratios and proportions
A bar model for a:b and each part's share of the whole.
Guide - Activity
Decimal multiplication model
A tenths grid: 0.a × 0.b counts hundredths cells.
Guide - Activity
Factors and multiples
List all factors of n and compute gcd and lcm of two numbers.
Guide
Measurement models
- Activity
Rectangle area
Area = length × width — tile with unit squares.
Open - Activity
Circle area
Slice a circle into sectors and rearrange toward a rectangle: S = πr².
Guide - Activity
Rectangular prism volume
Volume = length × width × height — pack unit cubes.
Open - Activity
Clock-hand angles
Minute hand 6°/min, hour hand 0.5°/min — find the angle between them.
Open
Number sense
- Activity
Number line and opposites
Drag a point on the number line to see opposites and absolute value.
Open - Activity
Absolute value geometrically
On the number line, |a| is distance to the origin; |a − b| is the distance between two points.
Open - Activity
Visual patterns (matchsticks)
Induce aₙ: n squares need 3n + 1 matchsticks.
Open