Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 726 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a magnet (d) a cotton bud
2. 2.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a balloon (d) a small bowl
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) the same paper (d) the iron setting
5. 5.⚖️ 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
6. 6.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
7. 7.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) dipping the cotton bud (c) putting the iron away (d) plugging in the iron
8. 8.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
9. 9.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
10. 10.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) ironing the paper
11. 11.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
12. 12.True or false: letting the paper dry is a job for an adult. (a) True (b) False
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) chemical (d) physical
14. 14.⚖️ 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 change it (c) we measure it
15. 15.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) ironing the paper (d) plugging in the iron
16. 16.🧺 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) white paper (d) a mirror
17. 17.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
18. 18.⚖️ 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) True (b) False
19. 19.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) wash your hands (d) rub your eyes
20. 20.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) writing the message (c) ironing the paper (d) plugging in the iron
21. 21.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
22. 22.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
23. 23.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) lemon juice (d) a battery cell
24. 24.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) ironing the paper (c) putting the iron away (d) plugging in the iron
25. 25.True or false: ironing the paper is a job for an adult. (a) False (b) True
26. 26.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
27. 27.🔮 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
28. 28.⚖️ 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
29. 29.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) an adult with an iron (d) a balloon
31. 31.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) cutting the lemon (d) putting the iron away
32. 32.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
33. 33.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) letting the paper dry (d) cutting the lemon
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) an adult with an iron
36. 36.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
37. 37.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
38. 38.⚖️ 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
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) how dark the writing is (c) the ironing time (d) the kind of juice
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False

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