Instead of starting with all the mixed-up blocks on the left (top) move all the mixed-up blocks to the solution area (bottom) to start and then students can move just the distractor blocks to the top (source) and can more easily rearrange the correct blocks especially on a limited display device like a phone.
Instead of starting with all the mixed-up blocks on the left (top) move all the mixed-up blocks to the solution area (bottom) to start and then students can move just the distractor blocks to the top (source) and can more easily rearrange the correct blocks especially on a limited display device like a phone.