Computer Science Education Week is held every December, in the week of Grace Hopper's birthday (December 9, 1906). She was a computer scientist and a rear admiral in the US Navy who helped make some of the first computer programming languages, so that people could write code in words instead of strings of numbers. Real robots and game characters are coded the way these puzzles are: they turn left or right from the way they are facing, and an if-then block lets the code check what is ahead and decide what to do, so one short loop can find its own way around the trees.
Seven pages of coding with no computer, the next level of Winter Coding Puzzles. Now the animal faces a way, shown by the arrow on its square, and the cards are forward 1 (one square the way it faces), turn left and turn right (a quarter turn on the spot, without moving). Page 1 is turns only: circle the way the animal faces after its turn cards. Page 2 follows codes of forward and turn cards: draw the path and circle what the animal gets. Page 3 writes the shortest code to the picture with F, L and R, one letter a box; each grid has just one shortest code. On page 4 one card is wrong: cross it out and write the right card. Page 5 brings in the if-then block inside a loop: each time round, if a tree is ahead the animal turns, else it goes forward 1. Page 6 fills in the missing part: circle the turn, or write how many times the loop must run. Page 7, for 4th grade, mixes loops, turns and two if-thens, and counts the snowflakes the animal picks up. The first problem on every page is worked as an example.
Before page 1, have the class stand and face the board, then turn right together, and again, saying which wall they face each time. Then turn to face the back and try turn left: it is the turn the other way from where you face, not from where the board is. Tape a grid on the floor and let one child be the arctic fox while another reads the cards. For page 5, the class reads the if-then out loud each time round the loop: is a tree ahead? Yes, turn. No, go forward.
Play robot: one person is the robot, the other gives it forward, turn left and turn right cards to reach a snack across the room. Then try a rule instead of a list: "until you get there, if something is in front of you, turn right, else take a step." Does the rule get the robot there?
The next level of unplugged winter coding, where the animal faces a way and the cards say forward 1, turn left and turn right, then if-then blocks decide what it does each time round a loop. Students track which way it faces, follow and write codes, fix a wrong card, run if-then rules, fill in a missing turn or count, and pick up snowflakes with loops, turns and if-then together.
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