Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 464 · 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.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a small bowl (d) a mirror
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
5. 5.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
6. 6.🔍 Which is the odd one out? (a) reading the message (b) ironing the paper (c) putting the iron away (d) cutting the lemon
7. 7.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) heat adds colour (d) the juice scorches first
8. 8.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) letting the paper dry
9. 9.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
11. 11.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
12. 12.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
13. 13.⚖️ 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
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the same paper (c) the same cotton bud (d) the kind of juice
15. 15.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a battery cell (c) lemon juice (d) white paper
18. 18.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) lick your fingers (c) rub your eyes (d) skip washing
19. 19.True or false: putting the iron away is a job for an adult. (a) True (b) False
20. 20.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) cutting the lemon (d) writing the message
21. 21.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) ironing the paper (c) writing the message (d) dipping the cotton bud
22. 22.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
24. 24.True or false: letting the paper dry is a job for an adult. (a) False (b) True
25. 25.True or false: plugging in the iron is a job for an adult. (a) True (b) False
26. 26.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
27. 27.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
28. 28.True or false: dipping the cotton bud is a job for an adult. (a) True (b) False
29. 29.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
30. 30.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) writing the message
31. 31.🧺 Do we need a mirror 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 same paper is kept the same. (a) False (b) True
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) lemon juice (d) a battery cell
34. 34.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
35. 35.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
36. 36.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
37. 37.🧺 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) lemon juice (d) turmeric powder
38. 38.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) an adult with an iron (d) a magnet
39. 39.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
40. 40.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed

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