The format of this book is simplistic. Even more disturbing is the need for an editor or proofreader with command of basic English syntax: when did "Math lessons" become "Maths lessons"? If the author uses a standard other than American English, an informative statement about the background of the writer should be ammended to this book when it is offered in the US. And when did self-publishing become carte blanche to ignore the use of standard English and the rules of grammar in anything other than works of fiction? The opening paragraphs in the introduction alone contain numerous grammatical issues: run-on sentences, plural possessive of a singular noun, and excessive use of commas (to name but a few errors).
The author laments, "Bad teaching at primary school caused [her] problems in [her] mathematical development that [she] only overcame towards the end of [her] secondary education." I lament as well that this same "bad teaching" spilled over from mathematics into grammar, affecting the writing in this book.
Self-publishing is a wonderful way to share information with others. Take yourself seriously as an author, however, by asking a qualified person to edit your material. Otherwise, many will only see what is surely the case here: rudimentary subject matter presented in a format that is elementary at best.
Those serious about teaching children, don't waste your time with this book.