Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 799 · 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.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a mirror (d) white paper
5. 5.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
7. 7.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) cutting the lemon (d) reading the message
8. 8.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
9. 9.⚖️ 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 keep it the same (c) we change it
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a magnet (c) lemon juice (d) an adult with an iron
11. 11.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
12. 12.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
13. 13.🔍 Which is the odd one out? (a) writing the message (b) ironing the paper (c) letting the paper dry (d) reading the message
14. 14.🛟 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
15. 15.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
16. 16.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
17. 17.🧺 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) lemon juice
18. 18.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) letting the paper dry
19. 19.True or false: ironing the paper is a job a child can do. (a) False (b) True
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) turmeric powder (d) white paper
21. 21.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) white paper (d) a balloon
23. 23.True or false: reading the message is a job a child can do. (a) False (b) True
24. 24.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) ironing the paper
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a cotton bud (d) yeast
26. 26.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) putting the iron away (d) dipping the cotton bud
27. 27.⚖️ 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) True (b) False
28. 28.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the same cotton bud (c) the ironing time (d) how dark the writing is
30. 30.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) reading the message (d) letting the paper dry
31. 31.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) writing the message (d) plugging in the iron
32. 32.⚖️ 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
33. 33.⚖️ 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 ironing time
34. 34.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
35. 35.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) writing the message
36. 36.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
37. 37.True or false: yeast is needed for the secret lemon message. (a) True (b) False
38. 38.⚖️ 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 ironing time
39. 39.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) reading the message
40. 40.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it

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