I would choose the activity on the planets as a focus for the lesson. My choice would be to create a scale model of the solar system, integrating art in the process. In order to do this there would have to be a lot of prior learning, the class would discuss the planets, their sizes and relative distances from each group. Children would be divided into pairs and assigned a planet to research, creating an index/information card on it.
Once children have made their own planets to scale, for example, 1 cm could be equivalent to 5 million km. I would have each group place their planet at the appropriate distance from a central “Sun’, either on poster board or hanging from the ceiling.
Following the lesson we would reflect and discuss on the learning and the scaled project would be left up for the year and used to elicit prior knowledge for future learning.