When is a number divisible by 2, 4, 5, 10? Animation Play

When is a theorem false? Animation Play

When is a theorem false? The counterexample Student activity Play

When is an assignment a function? Student activity Play

Which is bigger? Whiteboard exercise Play

Which is bigger? Student activity Play

Which is more probable? Student activity Play

Why are negative numbers necessary? Student activity Play

Women's handwriting and men's handwriting Whiteboard exercise Play

Women's handwriting and men's handwriting Student activity Play

Working with decimal notation Student activity Play

Working with mixed numbers Student activity Play

Working with mixed numbers Animation Play

Write the sum using powers of 10 Student activity Play

Write the sum. Place value Student activity Play

Write the sum. Place value Whiteboard exercise Play

Writing and solving the equation Student activity Play

Writing in the form of algebraic expression Whiteboard exercise Play

Writing numbers as the sum of powers of 10 Whiteboard exercise Play

Writing the sum using powers of 10 Animation Play

Wrong steps in reasoning Student activity Play

X-ray radiation Glossary Play

X-ray radiation Student activity Play

Yoko's and Lena's number Whiteboard exercise Play

Yoko's discovery Animation Play