Notify 1 minute, 2/minute, 4(2×2 = 4) minute and 8(2×4 = 8) minute. The number of people who received the notice doubled, but there was one more, ×2+ 1 or-1, as the case may be. ?
The lesson "Mathematics Wide Angle-Reasoning" is the learning content of Unit 9 in the second volume of the second grade of the new curriculum standard for compulsory education. It contains two contents: Inference 1 and Inference 2:
The textbook is mainly through simple examples in students' daily life, so that students can feel the reasoning process through operations, experiments, guesses, etc., and infiltrate mathematical ideas. Beijing Normal University Edition put these two contents in "Fun Mathematics-Filling Numbers Games" in grade one and "Fun Reasoning" in grade three, which makes people think deeply.