Hi Jill,
this can be treated as an investigation activity or a design and make using the results of their exploration with the materials.
It can be connected to “• explore how shadows are formed” – if they treat the darkness of the shadow as the desired condition. (from Infants Science)
Please note that 1st/2nd class has “• investigate the relationship between light and materials” and that the activity you are planning is an exemplar for 3rd/4th class (design and make a light shade for bedroom), so I’d check with colleagues that they don’t plan to do this later in the children’s school years.