Learn · Illustrative Mathematics K–5 · Grade 4 · Unit 3
Short lessons you can play with. Make equal groups of fractions, add and subtract with strips and jumps on a number line, plot measurements in eighths of an inch, and add tenths to hundredths, then check yourself.
Six short chapters follow the unit’s lessons in order. Each step shows one idea with something to tap or move, then a quick check. A wrong answer names the likely mistake and gives one more try. Progress is saved on this device.
Denominators are 2, 3, 4, 5, 6, 8, 10, 12, and 100, as in the unit, and fractions are only added to or subtracted from fractions with the same denominator (tenths plus hundredths is the one exception, after rewriting the tenths). Every operation is shown first with fraction strips, number lines, or a hundred grid, and answers above 1 are also written as mixed numbers.
Unit fraction: a fraction with 1 on top, like 1/5: one of the equal parts. Equal groups: 3 groups of 2/5 is 3 × 2/5. Mixed number: a whole number and a fraction, like 2 1/4. Line plot: a number line with an X for each measurement. Hundredth: 1 of 100 equal parts; 1 tenth is 10 hundredths.
Flexible with Fractions (Lesson 19) and Sticky Notes (Lesson 20) are optional lessons. Decimals come in Unit 4. Practice it all in Camp Fraction, the game for this unit.