Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 949 · 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 battery cell is needed for the secret lemon message. (a) False (b) True
2. 2.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) lemon juice (d) white paper
4. 4.True or false: letting the paper dry is a job for an adult. (a) False (b) True
5. 5.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
6. 6.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
7. 7.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
8. 8.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
9. 9.True or false: turmeric powder is not needed for the secret lemon message. (a) False (b) True
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the ironing time (c) the kind of juice
11. 11.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a balloon (c) yeast (d) a small bowl
12. 12.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) putting the iron away (d) dipping the cotton bud
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
14. 14.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
15. 15.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
16. 16.True or false: writing the message is a job for an adult. (a) False (b) True
17. 17.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
18. 18.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a mirror (d) a cotton bud
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
20. 20.True or false: reading the message is a job a child can do. (a) False (b) True
21. 21.🛟 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
22. 22.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) dry juice is see-through (d) it turned into air
23. 23.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) it gets darker (d) writing turns green
24. 24.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
25. 25.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) reading the message (d) putting the iron away
26. 26.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a balloon (c) an adult with an iron (d) a battery cell
27. 27.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the same paper (d) the kind of juice
29. 29.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) turmeric powder (d) a mirror
30. 30.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
31. 31.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
32. 32.True or false: cutting the lemon is a job a child can do. (a) False (b) True
33. 33.True or false: putting the iron away is a job a child can do. (a) True (b) False
34. 34.True or false: white paper is needed for the secret lemon message. (a) True (b) False
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
36. 36.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) reading the message (c) letting the paper dry (d) dipping the cotton bud
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) white paper (d) an adult with an iron
38. 38.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
40. 40.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed

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