Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 496 · 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) needed (b) not needed
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) lemon juice (d) a small bowl
3. 3.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
4. 4.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a cotton bud (d) a magnet
6. 6.🛟 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
7. 7.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) ironing the paper
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) a cotton bud (d) a small bowl
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a small bowl (d) yeast
10. 10.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) ironing the paper (d) writing the message
11. 11.True or false: letting the paper dry is a job a child can do. (a) True (b) False
12. 12.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) only an adult (c) whoever is fastest (d) the youngest child
14. 14.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) writing the message
15. 15.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
16. 16.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) putting the iron away (d) dipping the cotton bud
17. 17.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we keep it the same (c) we change it
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
20. 20.True or false: writing the message is a job a child can do. (a) True (b) False
21. 21.True or false: yeast is needed for the secret lemon message. (a) True (b) False
22. 22.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same paper
24. 24.True or false: plugging in the iron is a job a child can do. (a) False (b) True
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
26. 26.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
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 keep it the same (b) we measure it (c) we change it
29. 29.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
30. 30.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
31. 31.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
32. 32.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
33. 33.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) cutting the lemon (d) letting the paper dry
34. 34.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the same paper (c) how dark the writing is (d) the ironing time
36. 36.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) dipping the cotton bud (d) reading the message
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
38. 38.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a cotton bud (c) white paper (d) a battery cell
39. 39.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) writing the message (d) putting the iron away
40. 40.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it

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