Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 556 · 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: ironing the paper is a job a child can do. (a) False (b) True
2. 2.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) an adult with an iron (c) a magnet (d) a battery cell
3. 3.True or false: letting the paper dry is a job for an adult. (a) True (b) False
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) lemon juice (d) a magnet
5. 5.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
7. 7.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) letting the paper dry (c) plugging in the iron (d) ironing the paper
8. 8.🔮 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
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
10. 10.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
11. 11.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a battery cell (c) a balloon (d) a mirror
12. 12.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) writing the message (d) dipping the cotton bud
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a mirror (c) a magnet (d) a battery cell
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) lick your fingers (d) wash your hands
15. 15.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
16. 16.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) dipping the cotton bud (d) putting the iron away
17. 17.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
18. 18.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we keep it the same (c) we measure it
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a small bowl (c) an adult with an iron (d) white paper
21. 21.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) white paper (d) a cotton bud
22. 22.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the ink is magnetic (d) the paper ate it
23. 23.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
24. 24.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) a battery cell (d) white paper
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) white paper (d) a balloon
27. 27.⚖️ 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
28. 28.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
29. 29.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
30. 30.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it can burn skin (d) it is sticky
31. 31.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
34. 34.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing stays faint (d) writing turns green
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) white paper (d) a small bowl
36. 36.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
37. 37.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) letting the paper dry (d) ironing the paper
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) white paper (d) a battery cell
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) yeast (d) white paper
40. 40.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it

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