So Charms Homework was to produce the spell in five different places around the castle?

As Simon trekked up from his warm common room, he found himself on the first floor near all the portraits. He overheard some of the portrait's chattering about how cold it was in Hogwarts. The boy gave them a sympathetic look and then pulled out his wand. Some of the portraits gasped at him, asking him what he was doing pulling out his wand. "I'm going to cast a spell that'll make it warmer in here, okay? I'm not going to burn one of you to make the rest of you warmer, alright?" he said raising his hands up into the air. The portraits eyed him suspiciously. Simon just rolled his eyes and began his work.

Infinity sign and the incantation? Multiple times? He could do this. No worries.

Pointing his wand at the wall he began to move it in a sideways figure eight, "Caelum Saepio" He repeated it again and saw a little little cloud of fog appear against the wall. Aha! He had to keep on going. "Caelum Saepio!" he said in tandem with the wand movement. A bigger cloud of fog appeared. He did it one more time and figured that was enough.

Then Simon turned around to face the portraits. He bowed. "You're most welcome." With that he slipped his wand back into his sleeve and walked off to find another area of the castle.

One down. Four to go.