This is level 5 of the New Tunnel.
Since the size of the platforms are larger, you can pass this level more easily by using the Duplicator. Use high jumps to pass over the gaps, while jumping off duplicates to create "a double jump" when necessary.
If you want to use the Child, you can still do this by jumping high and float, this can bring you to unimaginable places, such as far far away, landing on platforms that you didn't plan to land. Which can be helpful sometimes.