Expansion of the lesson

 Main questions by teacher and anticipated students' responses Remarks on teaching Let's calculate 18 x 25 using your calculator. 18 x 25 = 450 Without using key "5", how do you calculate 18 x 25 on your calculator? Make sure every student calculates 18 x 25 with a calculator. Let students understand that they can use any other keys including "+", "-", "÷". Let students solve the problem individually. If students need help, give them the work sheet. Compare students' solution and find the ideas behind their solutions. 18+18+18+18+18+18+18+18+18+ 18+18+18+18+18+18+18+18+18+ 18+18+18+18+18+18+18=450 18 x 24 +18=450 18 x26 -18=450 18 x19 + 18 x 6=450 18 x100 ÷4=450 There should be many other answers. Ask the students who present their solution for other students to explain how to find the way to get the answer without using key "5", in order to help all other students understand the idea behind the solutions. Summing up by teacher. Teacher sums up all the ideas that students use to calculate 18 x 25 without using key "5". Exercise Calculate 18 x 25 without using key "2". Let each student write short journal about what he / she learned through this lesson.

Note; This expansion of the lesson should be based on a typical organization of the Open-Ended Problem Solving.