五年級(jí) 下冊(cè) 人教版 數(shù)學(xué)《兩數(shù)之和的奇偶性例2習(xí)題》課件

課題：兩數(shù)之和的奇偶性例2習(xí)題年級(jí)：五年級(jí)上/下冊(cè)：下冊(cè)版本：人教版1.復(fù)習(xí)兩數(shù)之和的奇偶性。學(xué)習(xí)目標(biāo)2.通過(guò)探究，知道兩數(shù)之積的奇偶性。復(fù)習(xí)引入奇數(shù)＋奇數(shù)=偶數(shù)例如：3+5=8奇數(shù)＋偶數(shù)=奇數(shù)例如：3+2=5偶數(shù)＋偶數(shù)=偶數(shù)例如：2+4=6同奇同偶一奇一偶、234+526=760、335+253=588、123+236=359復(fù)習(xí)引入不計(jì)算，判斷下面加法式子的和是奇數(shù)還是偶數(shù)？3+2奇數(shù)＋奇數(shù)＝偶數(shù)奇數(shù)＋偶數(shù)＝奇數(shù)偶數(shù)＋偶數(shù)＝偶數(shù)12+21125+8452598+5263和是奇數(shù)和是偶數(shù)733682873249601943173579742803294665813618390945264284664197202943770179521894164836772363071983143096380237+=奇數(shù)偶數(shù)奇數(shù)小研究2＋2＋2＋22＋22＋2偶數(shù)＋偶數(shù)=偶數(shù)和是偶數(shù)和是偶數(shù)和是偶數(shù)＋2幾個(gè)相同偶數(shù)的和是奇數(shù)還是偶數(shù)？小研究3＋3＋3＋33＋33＋33＋3＋3＋3＋3＋3奇數(shù)＋奇數(shù)=偶數(shù)偶數(shù)＋奇數(shù)=奇數(shù)和是偶數(shù)和是偶數(shù)和是奇數(shù)和是奇數(shù)幾個(gè)相同奇數(shù)的和是奇數(shù)還是偶數(shù)？小研究2＋2＋2＋22＋22＋2和是偶數(shù)和是偶數(shù)和是偶數(shù)＋23＋3＋3＋33＋33＋33＋3＋3＋3＋3＋3和是偶數(shù)和是偶數(shù)和是奇數(shù)和是奇數(shù)兩數(shù)之積的奇偶性探索發(fā)現(xiàn)4×6=6×8=2×4=6×6=5×7=3×5=7×9=3×9=5×4=6×7=9×8=2×3=2448634235721536278620=偶數(shù)偶數(shù)×偶數(shù)奇數(shù)×奇數(shù)=奇數(shù)=偶數(shù)偶數(shù)×奇數(shù)4×5=208×9=724×8=326×10=604×12=48……探索發(fā)現(xiàn)偶數(shù)×偶數(shù)=偶數(shù)偶數(shù)4×6=6×8=2×4=6×6=5×7=3×5=7×9=3×9=5×4=6×7=9×8=2×3=2448634235721536278620=偶數(shù)偶數(shù)×偶數(shù)奇數(shù)×奇數(shù)=奇數(shù)=偶數(shù)偶數(shù)×奇數(shù)4×6=246×8=482×4=86×6=36

舉例：2×4探索發(fā)現(xiàn)偶數(shù)×偶數(shù)=偶數(shù)2×42×4=2＋2＋2＋2偶數(shù)=4＋4偶數(shù)奇數(shù)奇數(shù)奇數(shù)×奇數(shù)=……5×9=459×11=993×13=39探索發(fā)現(xiàn)5×7=353×5=157×9=633×9=274×6=6×8=2×4=6×6=5×7=3×5=7×9=3×9=5×4=6×7=9×8=2×3=2448634235721536278620=偶數(shù)偶數(shù)×偶數(shù)奇數(shù)×奇數(shù)=奇數(shù)=偶數(shù)偶數(shù)×奇數(shù)奇數(shù)奇數(shù)×奇數(shù)=

舉例：3×5

3×53×5=3＋3＋3＋3＋3奇數(shù)=5＋5＋5奇數(shù)探索發(fā)現(xiàn)……8×5=406×11=669×10=90探索發(fā)現(xiàn)偶數(shù)×奇數(shù)=5×4=206×7=429×8=722×3=64×6=6×8=2×4=6×6=5×7=3×5=7×9=3×9=5×4=6×7=9×8=2×3=2448634235721536278620=偶數(shù)偶數(shù)×偶數(shù)奇數(shù)×奇數(shù)=奇數(shù)=偶數(shù)偶數(shù)×奇數(shù)偶數(shù)偶數(shù)探索發(fā)現(xiàn)偶數(shù)×奇數(shù)=舉例：2×3偶數(shù)2×32×3=2＋2＋2偶數(shù)=3＋3偶數(shù)探究發(fā)現(xiàn)偶數(shù)×偶數(shù)=偶數(shù)偶數(shù)×奇數(shù)=偶數(shù)奇數(shù)奇數(shù)×奇數(shù)=4×6=246×8=482×4=86×6=365×4=206×7=429×8=722×3=6………………5×7=353×5=157×9=633×9=27鞏固練習(xí)不計(jì)算，判斷下面乘法式子的積是奇數(shù)還是偶數(shù)？1×2奇數(shù)×奇數(shù)＝奇數(shù)奇數(shù)×偶數(shù)＝偶數(shù)偶數(shù)×偶數(shù)＝偶數(shù)56×5252×156786×58積是奇數(shù)積是偶數(shù)3637829221×1245

舉例：2×4偶數(shù)×偶數(shù)=偶數(shù)偶數(shù)×奇數(shù)=舉例：2×3偶數(shù)探索發(fā)現(xiàn)

小發(fā)現(xiàn)8100161101355720×6奇數(shù)偶數(shù)966