how to teach mathematics in Ist Grade using moodle?
Teaching with Moodle
In my opinion you don't need any advanced math tools to teach maths for first grade students ( and that page in moodle docs is not even up-to-date, tinymath could be used with moodle 2.0-2.3 but not with 2.4- )
Read a good book like "Moodle 2 for Teaching 7-14 Year Olds" by Mary Cooch https://moodle.org/mod/data/view.php?d=55&rid=5468
"Moodle 2 for Teaching 4-9 Year Olds Beginner's Guide" by Nicholas Freear https://moodle.org/mod/data/view.php?d=55&rid=5125
World wide web is full of free resources - activity sheets, games, all kinds of material ... and moodle is just a tool (learning environment) where you can add links to those resources, embed videos, add quizzes,... you can use for example normal quiz module to create quizzes like these nice examples in http://www.ixl.com/math/grade-1
Google gives thousands of pages like http://www.bestfreeonline.net/resources/free-math-resources/ but the main resource is your imagination