Home Models & Strategies · Grade 4 Fractions: Six Ways to Add & Subtract One problem, 3/5 + 4/5 = 1 2/5, worked six ways, from the models that build the most understanding to the rule that is fastest. every fraction is a COUNT of unit fractions 35= 15+15+15 45= 15+15+15+15 push them together: still all fifths 15151515151515 7 fifths=75 Count the unit fractions Read this one two wholes the SAME size, each cut into fifths 35 45 slide them together: 5 fifths fill the first whole 1 whole 25left over 35+45=125 solid = the first number · dashed = the second · orange = the whole just made Strip diagram · make the whole Read this one start at three fifths, and stop at the whole on the way +25+25 012 35125 jump to the WHOLE first, then the rest 45breaks into25+25 35+45=75=125 Number line · jump to the whole Read this one more than one whole: two names for one number 55=1 whole 25 75=55+25=1+25 75=125 and it breaks apart more than one way: 55+25·45+35·65+15 Improper fraction ↔ mixed number Read this one before you compute: about where should it land? 01 141234 3545 three fifths is a little more than a half · four fifths is nearly 1 so it must land between1and112 125fits ✓ Benchmark check · 0, ½, 1 Read this one the bottom number names the PIECE, so it does not change addingsubtracting 35+45 3 fifths + 4 fifths = 7 fifths =75 more than a whole, so write it the other way 75=125 add the top numbers · keep the bottom 125−45 2 fifths cannot give away 4 fifths borrow the whole back as 5 fifths 125=55+25=75 75−45=35 subtract the top numbers · keep the bottom The rule · add or subtract the top Read this one