Webinars SET A - Grade 3-4 - Sunday@3:15-4:15pm EST - 10 MEETINGS-Recording 3

Video Transcription

Video Summary

Sarah Sagee and teaching assistant Alex lead a Math Kangaroo webinar on using <strong>organized lists</strong> to solve problems with many possible outcomes. They review a four-step approach: carefully read the problem, identify key information, choose a strategy, and check the result. They also explain casework (“if this, then…”) and symmetry.

The students work through several examples:
- Making three-digit numbers from 3, 0, and 7 without repeating digits: <strong>4 numbers</strong>, since a number cannot begin with 0.
- Counting small cubes with exactly two painted sides in a 4×4×4 cube painted on five faces: <strong>20 cubes</strong>.
- Arranging a car, ship, airplane, and ball so the ship and airplane are both beside the car: <strong>4 arrangements</strong>.
- Finding the greatest possible book length when the digit 5 appears exactly 16 times in the page numbers: <strong>64 pages</strong>.
- Counting paths through a garden map from greenhouse A to B: <strong>8 paths</strong>, using symmetry.
- Opening the fewest locks to collect 50 coins from nested chests and boxes: <strong>8 locks</strong>.
- Counting Paula’s possible scores after two arrow shots: <strong>9 distinct scores</strong>, including zero for missing both times.

The presenters emphasize listing possibilities systematically, avoiding duplicates, and using labels or diagrams to keep track. They encourage students not to worry about mistakes: understanding the explanation and applying the method to future problems matters most.

Keywords

Math Kangaroo

organized lists

casework

symmetry

combinatorics

systematic counting

problem solving

three-digit numbers

nested chests

arrow scores