My implementation in Scheme of the game Kinema, that was published in BASIC Computer Games in 1978.

gamekata-kinema.csm

(use srfi-13 extras)

(printf #<<EOF

                   KINEMA
  Adaption of BASIC computer game from 1978

EOF
)

(define correct-count)

(define (prompt-and-evaluate-answer question answer)
  (display question)
  (display "? ")
  (let ((G (read)))
    (if (> .15 (abs (/ (- G answer) answer)))
      (begin 
        (display "Close enough.")
        (set! correct-count (+ correct-count 1)))
      (display "Not even close...."))
    (printf "Correct answer is ~A\n" answer)))

(define (main)
  (newline) (newline)
  (let* ((velocity (+ 5 (random 35)))
         (time     (/ (+ 1 (* 2 (random velocity))) 10)))

    (set! correct-count 0)
    (printf 
      "A ball is thrown upwars at ~A meters per second.\n\n" 
      velocity)
  
    (prompt-and-evaluate-answer
      "How high will it go (in meters)"
      (* .05 (* velocity velocity)))
  
    (prompt-and-evaluate-answer
      "How long until it returns (in seconds)"
      (/ velocity 5))
  
    (prompt-and-evaluate-answer
      (sprintf "What will its velocity be after ~A seconds" time)
      (- velocity (* 10 time)))
  
    (printf "\n~A right out of 3." correct-count)
    (when (> correct-count 2) (display "  not bad!"))
    (main)))

(main)