Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 850 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
2. 2.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) cutting the lemon (c) putting the iron away (d) ironing the paper
3. 3.True or false: a battery cell is needed for the secret lemon message. (a) True (b) False
4. 4.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
5. 5.True or false: reading the message is a job for an adult. (a) True (b) False
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) the same paper (d) how dark the writing is
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) a cotton bud (d) a battery cell
9. 9.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a mirror (d) a small bowl
10. 10.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
11. 11.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
12. 12.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
13. 13.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) yes, if shaken (c) yes, in the dark (d) no, it stays brown
15. 15.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
17. 17.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) a balloon (d) an adult with an iron
20. 20.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
21. 21.True or false: letting the paper dry is a job a child can do. (a) True (b) False
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) turmeric powder (c) white paper (d) lemon juice
23. 23.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
24. 24.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
25. 25.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
26. 26.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) plugging in the iron
27. 27.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
28. 28.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
29. 29.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
30. 30.True or false: cutting the lemon is a job for an adult. (a) False (b) True
31. 31.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a mirror (d) white paper
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the same cotton bud (c) the kind of juice (d) the ironing time
33. 33.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) reading the message (d) letting the paper dry
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
35. 35.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) white paper (d) yeast
37. 37.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
38. 38.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) False (b) True
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True

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