Revision of the basics from last time:

• Gave her a quick revision test: (+ 3 4), (- 7 5), (* 5 2) and so on. No problem, apart from needing clarification that (- 7 5) is the same as 7-5, not 5-7. (Interestingly, has developed a way of expressing negative numbers: 5-7=0-2. Where did she learn that?)
• Extended to multiple operands: (+ 3 1 2), (* 2 2 3) and so on. She had a brainfart with some of it, but worked it out with hints.
• Trick questions: (* 4 7 13 64 12 7 18 0). She lost confidence and wouldn’t even try, until I took her through each step encouraging her not to worry about the answer. To get better at maths in general, she needs to know to look for shortcuts wherever possible.
• Fired up the CLISP program and she typed in the same expressions, getting the hang of the fiddly details involved: spaces, parentheses, the enter key and so on. Quickly took to entering huge expressions just to see it print really big numbers, which LISP can do because it doesn’t suffer from the same numeric limits as most languages.
• Had to be dragged away after about twenty minutes so we could watch Heroes together.