Review: fractions and decimals
Fractions: a fraction names equal parts of a whole. A mixed number and a fraction greater than 1 can name the same amount: 2 3/4 = 11/4. To add or subtract fractions, the denominators must be the same, and we only add or subtract the numerators. When we subtract mixed numbers and the first fraction is smaller, we regroup one whole. To compare, use equal denominators, equal numerators or the benchmarks 0, 1/2 and 1. Equivalent fractions come from multiplying or dividing the numerator and the denominator by the same number. A whole number times a fraction is repeated addition: 4 × 3/8 = 12/8. Decimals: the first place after the point is tenths and the second is hundredths. 0.07 is 7/100 and 0.7 is 7/10. To compare or add decimals and fractions, give them the same number of places or the same denominator, 100. Add zeros on the right, never between the point and the digit.
| Idea | Example |
|---|---|
| Mixed number ↔ fraction | 2 3/4 = 11/4 |
| Equivalent fractions | 2/3 = 4/6 |
| Add mixed numbers | 1 2/5 + 2 4/5 = 4 1/5 |
| Fraction × whole number | 4 × 3/8 = 12/8 |
| Decimal as a fraction | 0.07 = 7/100 |
| Add tenths and hundredths | 3/10 + 27/100 = 57/100 = 0.57 |
Fraction and decimal stations. Write ten cards: five with fractions or mixed numbers (like 17/5 or 3 1/4) and five with decimals (like 0.45 or 0.6). Pick two cards and decide: can you add them, compare them, or write one as the other? Do it, check with a picture, and explain to a friend.