It can be difficult for children (and adults) to get orientated within the Bible with particular scriptural readings.
These 4 sentences (2 covering the Old Testament and 2 covering the New Testament), courtesy of Scripture Union's "Light" X-Stream lesson for 24 January 2016, can be helpful if you are starting a lesson or reading and want to get everyone clearly focused in their mind as to which part of the Bible you are learning about.
God made the world and wanted people to choose to love him.
God sent messages through kings and prophets, but people often chose not to love him.
God sent Jesus to die and come back to life so that people could choose to love him.
God sent the Holy Spirit who gave God's people power to tell others that they could choose to love God.
These four sentences, in the order given, are a summary of the whole Bible.
Another similarly helpful tool is the Bible Timeline produced by Scripture Union.