Level 2: Rules and puzzles

Logic and puzzles · level 2 of 8 · rough age 7-8 (a guide for parents; anyone can start anywhere)

In level 1 you sorted things and solved riddles by crossing out what could not be. In this level the same ideas grow into real puzzles. You decide whether a sentence is always, sometimes or never true, and prove it with a picture; sort with overlapping hoops; solve 4 by 4 Sudoku with two moves and no guessing; write and debug arrow programs; get a wolf, a goat and a cabbage safely across a river; and fill in logic grids with ticks and crosses.

Lesson	You will be able to
Always, sometimes, never	Show "sometimes" with two examples, break "always" with a counterexample, and prove "always" with a reason that covers every case
Sorting circles	Sort into two overlapping hoops, read the four regions, and use the overlap to solve counting puzzles
4-by-4 Sudoku	Solve 4 by 4 Sudoku with "only number for this square" and "only square for this number", and explain why a good puzzle has one answer
Coding with steps	Write and trace arrow programs on a grid, find the shortest program, explain why order matters, and debug wrong, missing and extra steps
River crossing	Solve the wolf, goat and cabbage puzzle by trying every choice and going back, and explain why 7 trips is the fewest
Logic grid puzzles	Use a grid of ticks and crosses, spot hidden "not" clues, and check that a puzzle has exactly one answer

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