Webinars SET B - Grade 5-6 - Sunday@4:30-5:30pm EST-Recording Webinar 9

Video Transcription

Video Summary

The webinar is a Math Kangaroo geometry lesson focused on building problem-solving skills and using diagrams, vocabulary, and creative reasoning. It begins with a warm-up about a square and a point’s distances from a vertex and a side, solved by finding triangle area using base × height (answer: 10 in²). The instructor emphasizes knowing standard area and perimeter formulas and being ready to apply them in contest-style ways, including surface area (painting) and 3D reasoning (faces, edges, vertices, nets, and viewing objects from different perspectives).<br /><br />Several sample contest problems are worked through. One problem finds the perimeter of a four-pointed star formed by equilateral triangles on a square, using circle radii to deduce a side length of 20 and then multiplying by the number of outer sides (answer: 160). Another problem involves overlapping squares; the area is found by adding individual areas and subtracting overlaps (answer: 51 cm²). A surface-area comparison of cube stacks is solved by noting that more “protruding” cubes expose more faces, giving the largest surface area to figure A.<br /><br />Additional problems include finding the perimeter of a rectangle subdivided into smaller rectangles (answer: 30), identifying an impossible view of a ribbon-wrapped transparent cube (answer: E), counting remaining cubes in a 5×5×5 cube after tunnels are cut (answer: 88), and a paper-folding area question using proportionality (answer: 16 cm²). The session closes with advice: look for shortcuts, know multiple methods, and practice full timed past contests.

Keywords

Math Kangaroo

geometry webinar

problem-solving strategies

area and perimeter formulas

diagram-based reasoning

surface area of cubes

3D geometry nets and views

equilateral triangle star perimeter

overlapping squares area

5x5x5 cube tunnels counting