Invalid argument supplied for foreach()

[Marco_Antonio_Veloso]

<?php foreach ($lista_tarefas as $tarefas): ?>//Undefined variable: lista_tarefas

		<tr>
			<td><?php echo $tarefas['nome']; ?></td>
			<td><?php echo $tarefas['descricao']; ?></td>
			<td><?php echo $tarefas['prazo']; ?></td>
			<td><?php echo $tarefas['prioridade']; ?></td>
			<td><?php echo $tarefas['concluida']; ?></td>
		</tr>
	<?php endforeach; ?>