Grades 3-4 Video Solutions 2025-2025_3-4

Video Transcription

Question 12. Which two of the pieces shown complete the chessboard? The pieces can be rotated, but cannot be flipped.  Let's start this question off by looking at piece number two. If we look at it, we know that we can rotate it. In its current state,  it does not fit anywhere. If we rotate it in any way, we see that it will still not fit. So option two cannot be the answer, or part of the answer. So A will be excluded.  Next, we'll look at piece number four.  Again, if we rotate it any which way without flipping it, we see that it will not fit in either of the holes.  So any solution with option four is wrong, so we can cross out C and E.  Now we are left with pieces 1, 3, and 5.  We know that piece 5 has to fit in that bottom hole, and then we are left with a question. Do we use piece 1 or 3?  Let's turn piece 1 so that it fits.  And since this is a chessboard, we know that it will alternate between black and white.  So looking at these two options,  we see that the answer will have to be B, pieces 1 and 5.

Video Summary

The task involves determining which two pieces can complete a chessboard by rotating the pieces but not flipping them. Upon examining each piece, it's determined that piece 2 and piece 4 won’t fit in any orientation. Consequently, options involving pieces 2 and 4 are eliminated. With pieces 1, 3, and 5 remaining, piece 5 fits in one segment of the board. By rotating piece 1, it fits appropriately while maintaining the chessboard's alternating black-and-white pattern. Thus, the correct pieces to complete the chessboard are pieces 1 and 5, corresponding to option B.

Keywords

chessboard

pieces

rotation

alternating pattern

option B