Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 916 · 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: turmeric powder is not needed for the secret lemon message. (a) False (b) True
2. 2.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) plugging in the iron
3. 3.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
4. 4.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) reading the message
5. 5.🧺 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) a cotton bud
6. 6.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
7. 7.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a magnet (c) white paper (d) lemon juice
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
11. 11.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) the youngest child (d) whoever is fastest
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a battery cell (d) a mirror
13. 13.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the kind of juice (c) the iron setting (d) the same paper
15. 15.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
16. 16.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) cutting the lemon (d) dipping the cotton bud
17. 17.🔍 Which is the odd one out? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
18. 18.True or false: putting the iron away is a job for an adult. (a) True (b) False
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the same cotton bud (c) the ironing time (d) how dark the writing is
20. 20.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
21. 21.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
22. 22.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) magnetic (c) musical (d) chemical
23. 23.⚖️ 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 measure it (c) we keep it the same
24. 24.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) a balloon (d) turmeric powder
25. 25.⚖️ 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 kind of juice (c) the iron setting
26. 26.True or false: reading the message is a job for an adult. (a) True (b) False
27. 27.⚖️ 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 measure it (c) we change it
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
29. 29.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) the paper floats (d) it gets darker
30. 30.⚖️ 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
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) an adult with an iron (d) lemon juice
32. 32.True or false: yeast is needed for the secret lemon message. (a) True (b) False
33. 33.⚖️ 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
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
35. 35.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a battery cell (c) a balloon (d) a small bowl
36. 36.True or false: white paper is needed for the secret lemon message. (a) False (b) True
37. 37.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) dark brown words (d) blue words
38. 38.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
39. 39.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
40. 40.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed

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